In this world King Arthur survived the battle of Camlann, and went onto finally bring the Saxons and Angles and Jutes to heel, although by compromise and winning brave Saxon knights to his service rather than by driving them into the sea, and to this day the Counties of the Saxon Shore speak Germanic tongues as much as the Latino-Brythonic of the royal court. He would going on rebuild the broken Round Table, and again begin the long struggle to secure the British foothold on the continent against the barely Christian Franks, but more cautiously; pride and overreaching himself had nearly ruined all he built, and no longer would he pursue the crown of western Rome he had taken from Syagrius’s shaky hands. But he would never renounce his claim. His old rival Lucius Tiberius would be overthrown by Odoacer, making Italy a Gothic kingdom, the Kingdom of Africa would fall to Justinian the Restorer and his descendants would achieve what he had failed to do, driving the Franks north of Loire, and in time marching upon an Italy ravaged by Eastern Romans and Lombards. The Viking age would end early, in a series of *Crusades against the pagan Norsemen.
By modern times (the 13th century), the British kings had restored to western Empire to an extent unmatched by the Franks of OTL, ruling over a somewhat decentralized constellation of ten kingdoms,  but one held together by the rules of primogeniture and formidable (mostly Church-staffed) bureaucracy. Unfortunately, much of the old Empire and the lands of Christendom remained outside the reach of Camelot’s rule, for another great ruler had succeeded where in other worlds he had failed: Harun El Rashid, greatest of Abbasid monarchs of Baghdad, after much sneaking around disguised as a commoner, had realized the extent to which the pious multitudes had become estranged from the ruling elite, and the investigations of his (quite loyal) vizier Jafar had revealed how weak the hold of the Caliphate were in its more distant regions. They set about doing something about it, creating new institutions and placing the Caliphate on a more solid footing, aided by magic and wisdom not available in our more mundane world.
In years that in our world would see the Caliphate overrun by Islamicized but still semi-civilized Turks, broken into fragments, embarrassed by Christian Crusaders, and devastated by Pagan Mongols, would instead see it break the Eastern Romans in Anatolia so they would only be saved from total collapse by the aid of the British kings, expand greatly into India and Africa, beat back the invaders from the steppe at the gates of Nishapur, and recapture Al-Andalus, while reaching new heights in the arts, wealth, and the sciences magical and otherwise.
So as the 13th century began, two great powers, one Christian, one Muslim, stood toe to toe across bloody frontiers. Each had an ally to serve as a strong right hand, although unfortunately for Baghdad, their “strong right hand” was on the wrong side of the continent to effectively help with the Christians, Islamic North China being often reluctant to send troops the length of Asia to bolster the Caliph’s efforts, while the Holy British Empire’s ally, the kingdom of Abyssinia, ruled by the descendants of the great Prebyster/Prester John, was all too well positioned to attack Islam in the Nile Valley or south Arabia or the east African coast (OTOH, it’s not like the Holy Roman Empire of the British Empire, as it had somewhat presumptuously come to call itself by that point, was in any position to actually send troops to Abyssinia’s aid).
And then the elderly master traveler, perhaps feeling nostalgia for his youth, decided on one last trip, and Sinbad the Voyager took ship from a port on the Moroccan Atlantic coast. And not long after, both the Caliphate and the British had a rather massive distraction from battles in Iberia, Anatolia, and the Mediterranean.
In this world, both Arthurian romances and the Arabian Nights are very much fact based, even if the details are often a bit off. Magic, giants, dwarves, genies, unicorns, dragons, elves, fairies (not clearly two separate categories), trolls, ghouls, the Rukh, the Great Sea Serpent, island fish, wizards, witches, hags, witch hags, sorcerers and sorceresses, basilisks, wodewose, dog-headed men, were-hyenas, one-horned killer rabbits, and much more are quite real, if not in many cases as common as they used to be.
Wizards and witches are more often evil or at least Out For Number One than good, and are looked upon with considerable suspicion, existing somewhat off to one side of the regular social hierarchies of the Islamic and Christian worlds. Islamic potentates are more likely to have resident “court wizards” on retainer, wizards in the Christian world being more likely to be called on in an ad hoc basis, or voluntarily attaching themselves to some court. (Merlin, who was eventually freed from that tree, is still alive, but only shows up at the royal court on the most urgent of occasions, something most nobles don’t mind- he’s only gotten weirder over the centuries). Some powerful wizards and sorceresses establish petty kingdoms of their own on islands, etc. These usually end up being overthrown by some Knight or valiant Vizier or Hero of whatever background, or by other wizards.
Warfare between Christian and Muslims realms is currently a matter more of border clashes than major assaults, with both sides taking roughly equal honors, Christian heavier armor vs. greater Islamic mobility, a somewhat higher percentage of Ludicrously Strong fighters on the Christian side balanced by an edge in magic on the Muslim side. A shortage of good timber somewhat hampers the Muslims navally, while Arabian flying carpets and wooden horses have an advantage in both numbers and carrying capacity over difficult to tame flying Griffins and very hard to breed hippogriffs.
In Christian Europe, the social hierarchy is a bit “flatter” than in our High Middle Ages: the gap between the higher and lower nobility is not as great, and there are less restrictions on who can marry who (a simple knight can marry a princess, if he comes with a laundry list of knightly deeds (slaying dragons, capturing bandits, freeing maidens from durance vile, etc.), and is sufficiently brave and courtly and doesn’t smell too much of horses). The king-emperor still seats his guests at a round table regardless of rank (although it is true that it is a large enough table that the number of seats between you and the king is significant.) There is a sizable free peasant class, although neither they nor the free burghers of larger towns have much say in government.
The Christian west is somewhat more tolerant than OTL; dating back to the times of Arthur (who cut deals with still pagan Saxons and whose friend Merlin was hardly a church goer) there is a certain degree of tolerance for backwoods heathens as long as they don’t try to spread their faith and don’t sacrifice anyone (most Lithuanians are in fact still pagan). Jews also are not as badly off as OTL; they are under a variety of legal disabilities, but are at little risk of the local villagers or petty nobles doing a murder-and-loot on their Jewish community: they are under the protection of the King-Emperor, and trash-talking by the Church is kept to a minimum. Due to their enemy status, the only Muslims are traders confined to some port cities. There is some species tolerance: dwarves, giants, and even ogres can gain social standing and even become knights if they convert to Christianity. (The Fey Folk, as will be discussed further on, are a whole other kettle of fish). Women often have some power, aside from noblewomen and female merchants and scholars fairly literally so in the case of witches and sorceresses, and there are also some female knights (although they are generally expected to settle down and stop gallivanting around in armor when they get married).
Knights and other nobles do the fighting, with levies of peasants and townsfolk playing a lesser role than they would in our world. This is to some extent because the warrior class is simply more powerful than in our world: even before you get to things like enchanted weapons or supernatural steeds, one can gain some degree of Charles Atlas Superpowers through sufficiently training in the arts of combat, while nobility and purity of purpose can empower one: pure heart can literally give one the strength of ten. Fortunately for their opponents, such tree-uprooting, city-taking, giant-pounding heroes are pretty rare. (Not all Christian human heroes are of noble origin: there are the occasional clever-ass peasant boy or girl, innocents Of Unusual Strength, and the occasional guy raised by bears or something).
Interestingly, purity of purpose and faith sometimes inspires superhuman strength in Muslim warriors as well, evening up the odds a bit in battles: the Church usually ascribes this to the aid of Satan (the Muslim Ulema, on the other hand, less quick to pin things on Iblis, explains superpowered Christian warriors as the result of black sorcery and possibly cannibal rites).
Technology is generally a couple centuries ahead of OTL, being more on a late 1400s level: there are windmill and watermill industries, armor is plate, compasses are well known, and the printing press has recently arrived from China. Gunpowder arrived not that long ago, although thanks to the somewhat superhuman nature of some troops and the presence of magic it has not yet become important on the battlefield, although it is increasingly becoming used in castle fortification demolitions. (Magic on the battlefield is a tricky thing. Aside from magical weapons, magicians, being generally of a non-physical type usually work from a distance, and generally only can strongly sway the outcome if the other side has no wizards of their own - it’s generally easier to screw up another mages workings than to carry out a magical assault of your own).
Magic does not, as yet, and perhaps never will, take the place of more advanced technology. The production of magical tools and weapons is an exacting, time consuming craft, carried out by magicians, the faye, and dwarves (which have a talent for that sort of thing) and can’t currently be mass-produced. Perhaps the biggest magic-derived difference from OTL when it comes to the life of the average John in the cowpath is that herbalists, alchemists, etc. can produce medicines which actually _work_ rather than doing nothing or making things worse: while the poorest still can’t afford it, the general death rate from disease is rather lower than in our 13th century, and if it weren’t for midwife-witches doing a brisk business in effective anti-conception charms and herbal remedies, the continent would be badly overpopulated by this point.
Tensions exist between Throne and Church. The Papacy, although treated well by the King-Emperors after they ended Lombard rule in Italy in the 600s, have not achieved the level of power they did in the High Middle Ages OTL: while the King-Emperors have not gone full Caesaropapist the way the Byzantine emperors did and accept the Pope’s independence in ruling on religious matters, they do not accept him as having any _secular_ authority. While they did gain control of a big chunk of Central Italy (although assured by his mages that the whole “Donation of Constantine” was a total crock, the king at the time was feeling indulgent), they rule it as secular subjects of the Emperor: even Rome itself is not theirs alone, being divided between Church property under Papal control and secular land (most of the city, actually) belonging to the Emperor. The Church failed to gain the vast territories in Germany it did OTL, and the fact is they have no other secular Christian monarch strong enough to stand up to Camelot on their behalf. (Exactly one Pope had the balls to try and excommunicate the King-Emperor over a quarrel, and he didn’t last long). The Popes also are in disagreement with the Emperors over the status of Romelia, whose local priesthood is self-selecting and separate from the hierarchy of Rome (the Great Schism of OTL did not take place, but the Archbishop of Constantinople continues to refuse to accept the superior authority of the “Bishop of Rome”) thanks to some irritating doctrinal differences: preferring peace and obedience to religious purity, the Emperors refuse so far to carry out the forcible unification of the Church.
The Church has a variety of powerful relics, but continues to lack the Holy Grail, which is currently in the back pack of the last and most loyal of Arthur’s knights, who walks the pilgrim routes of Europe in simple garb and occasionally helps those in need he meets. If it is ever truly needed, he’ll be there: in the meantime, as long as nobody knows what’s in his backpack, the grail is safe from evil men or from well-intentioned but over-ambitious kings, emperors, and popes.
In most of Eurasia, the population of supernatural beasties and critters is rather down from previous centuries. Wicked giants, ogres, dragons, ghuls, trolls, etc. have been wiped out or driven into narrow patches of territory, (the last wild flying Dragons in Europe are hiding out somewhere in the Carpathians) unicorns hunted down for their horns, and evil spirits banished. There are still large areas where unnatural forces dominate, but the world has become more secure for common folk. The biggest remaining problems of a supernatural type are, in the Islamic lands, the Djinn, and the Sidhe, Fey, or Alfen in the Christian realm, both diverse families of creatures with powerful magic and dangerous dispositions.
They say that the courts of Fairie are distinct. First there are the Fey which are mysterious, scary, treacherous, unreliable, fond of nearly lethal pranks and frightening curses. Then there are the Fey of the Unseelie court, the nasty ones.
Fey still rule great areas underground beneath Ireland, western Britain, and parts of Scandinavia, and have at least footholds in many parts of the continent. Under the Sidhe, their ruling elite, they still form something a state within a state in the territory of the King-Emperors of Britain, although since their defeat centuries ago at the hands of Christian armies armed with cold iron and prayer (and some wizardry) they have recognized the King-Emperors as their liege lords and the above ground world as something not to be tampered with. Still, the many minor races of Fey still occasionally cause trouble (the Sidhe claim they can’t do anything with solitary and nomadic red caps, bugbears, etc.) and through bribery (not all fairy gold is fake) and enchantment and gifts of magic the Sidhe seek to manipulate and control the noble classes of Christendom. Being immortal save when killed, the Sidhe play a long game, and there are other entanglements: there are nobles with fey blood in their family lines, and there are descendants of human knights dwelling in the fey lands, and who was that lady of the lake anyway? If the Empire had tabloids, they’d be all over high members of the Court secretly meeting with elves and seductive fairy queens up to no good and so on.
The Caliphate has rather less control over the Djinn, it's own main magical headache. While the Seelie and Unseelie courts do maintain at least some control over their many unruly subjects, the title of ‘Emperor of All Djinn’ is almost wholly a ceremonial one. Djinn are magically potent entities who can live on the wind or in sand or stone, need no cities, and can travel the length of a continent in a night. Unlike humans or Fey, they have little need for company and rarely aggregate in great numbers save when observing humans doing something particularly amusing. There is no “Djinn kingdom” that can be localized and besieged, although there are some areas where they are pestiferously abundant and humans avoid like the plague. Although many Djinn are Muslims and at least nominally subjects of the Caliph, they aren’t at his, or any other humans, beck and call. They come in many forms, or perhaps they have no fixed form, some appearing as beasts, other times as people with horns or hoofed feet, or as beings with no heads or who are all head or as clouds or sandstorms.
King Solomon long ago imprisoned most of the more dangerous and troublesome Djinn, the majority of them in bottles. Opening these can be a crapshoot, since the Djinn inside may be in either a generous mood or a murderous one. Djinn which are slaves to an enchanted artifact and can grant any number of wishes, such as the Slave of the Ring or the Slave of the Lamp are very rare, and therefore very intensively hunted for by wizards and powerful men (and women). (Unlimited numbers of wishes, but not wishes without limits: there are certain things one cannot wish for and allow an angered Djinn to kill its master, which generally discourages casual/thoughtless use of magic lamps and such).
King Solomon’s Ring, which can command the obedience of all genies, is an artifact of such power that the monarch who gets their hands on it will probably be the ruler of the world, but is very well hidden.
The Caliphate is a more centralized realm than the British Holy Roman Empire, with standardized provinces and, in all but a few areas, appointed governors. This has not been achieved without bloodshed, and keeping the nomads peaceful and non-bandity remains an exercise in herding cats: even with magic, flying carpets, etc. it’s a huge area to keep track of, and there has been considerable realism in letting north China and the Indian states govern themselves. (As well as some racism: the Persian peoples have only recently reached full social equality with the Arabs, the Berbers and Turks are still getting there, and all three are if anything more opposed than the Arabs to the possibility of the status quo being overturned if culturally alien Chinese and Indians become the majority of the Empire). With better healthcare, magical and otherwise, more developed agriculture, and continued peace the Caliphate is more populous than the equivalent area OTL, but still not so much as India and China.
It’s also a more egalitarian state, the Caliphs having worked to try and prevent the rise of any powerful regional nobility (with some exceptions for Arabia proper and the always troublesome mountainous east), and even those of humblest origin, including converts to Islam from any faith, can rise very high. The treatment of Christians and Jews is OTL Moorish Spain at its best, and while things are harsher for polytheists there are special dispensations for Hindus and Buddhists in the east, where they are too numerous to simply offer the choice between conversion, expulsion, or the sword. Race is less important than culture: the color of your skin is not as important as your ability to speak good Arabic or Persian. (Indeed black Africans are more highly regarded in the Arab world than OTL at this time: the great empire of Prester John is a constant reminder that black Africans can be highly sophisticated, and some citizens of the Caliphate consider Abyssinia a more civilized place than Christian Europe).
While the state remains an absolute monarchy with the Caliph as essentially the Shadow of God on Earth, there are permanent advisory bodies at multiple levels of administration to keep close contacts between populace and government, and some cities are largely run by the powerful mercantile clans, while an extensive spy network answerable only to the Caliph keeps him advised as to the real skinny. The military is a mix of slave armies, nomadic mobile auxiliaries, and unlike OTL, something like a free professional class of soldiers as well as mass levies, to counterbalance the slave soldiers: some Caliphs have tried to eliminate this, but never have permanently succeeded, being opposed by the Ulema, local elites, and the writings of Harun himself, who warned of the dangers of a slave military taking control of the state right out of the hands of the Caliphate itself. (He’d been taken on several vision trips to other worlds by wizards and Djinn to figure out what to do). As in Europe, giants, ogres (the eastern type, the kind with tusks and elephant ears) and occasionally even Djinn up for a lark serve at times in Muslim armies.
It’s a richer and more developed place in many ways than Europe, although troubled by its vast interior empty spaces and deserts and the resultant difficulties of transportation, and the narrow concentration of its fertile land. Magic is even more common than in Christian Europe, with a large class of alchemists and magical crafts-workers producing marvels and wonders, plus the often treacherous creations of the Djinn. The luxuries of the rich are more luxurious, the markets finer, and the gardens more wondrous. OTOH, there are rather a lot more slaves (although a sharp-witted Muslim might comment that Christians have serfs instead), and while there are female scholars, merchants, and mages women generally lead rather more restricted lives (the Wife of Bath would be an unlikely Arabian Nights character) and the laws are often harsh (and they don’t even allow trial by combat, outraged Christian Knights complain). Aside from nomad protection rackets, magically-assisted bandits, Djinn, trouble-making wizards, and ambitious local notables, the main internal problem is the “Ali cult” or the Shi’a, who continue to deny the legitimacy of any Caliph not descended from the Prophet’s son-in-law(one Caliph in a peace-making mood married a woman descended from his line, and made her son his heir, but most Shi’a simply denied the legitimacy or even the existence of her family relationships): in one of his various minor acts of defiance, the Sultan of Cathay is far too tolerant of those living under his rule.
Unlike OTL, the Muslims have windmills too, and are in fact in somewhat ahead in a number of fields of technology as well as having more magicians per square mile. In fact, technological progress (not that they call it that) is important to both the Caliphate and the British Empire: the Caliphs have long promoted learning of all types and supported scholars mystical or holy or mundane, and Arthur himself worked to revive Roman learning in Britain, with many of his successors sending missions to the Byzantine lands to copy as much ancient wisdom practical as well as philosophical they could lay their hands on. There are a multitude of Islamic “houses of wisdom” and *universities teaching quite a bit more than Koranic exegesis, and an abundance of schools are popping up all over Christian Europe.
There are also a few “schools for sorcery” where magic undergoes rigorous study by scholars both wizardly and not, under government supervision, but such work is hampered by the fact that most powerful wizards won’t work under such restrictions, and most teaching of magic takes place as master to pupil mentorship or at “hidden schools” outside of government authority, and sometimes downright in defiance of it. (The situation is no better in Christian Europe, where the only real deliberate study of magic done in an organized setting is carried out by the Church. )
Outside the Caliphate the main Islamic power is the Sultanate of Cathay in North China, as the main Christian power outside the HREBN is The Blessed Kingdom of the House of Prester John (known as Abyssinia for short).
Most of China was overrun by the Caliphate as the T’ang disintegrated, and along with Arabs a vast number of Islamicized Turks settled in the north, not having much luck doing the OTL “take over the Arabic Empire” routine. Sheer geographical distance from Baghdad eventually led to secession, and currently an Islamic but native Chinese dynasty rules north China, the south having rallied to Traditional Chinese Values under the southern Qi dynasty. North China is more Turkish than Arabic, and more Chinese than Turkish, and has culturally diverged widely from the Caliphate : although in theory a vassal of the Caliph, the Sultan grows weary of this role, and has ambitions to conquer south China and maybe even declare himself an anti-Caliph: besides his numerous and wealthy subjects, he has a bit of a trump card in the form of a certain Ring and a certain Lamp. (Of course, he in turn is unaware of what the Caliph has in the deepest vaults of his treasury).
Abyssinia feels it owes little to Britain, although occasionally wizards and knights from Christian Europe have been very helpful. It reveres Prebster Johannes, priest, king and wizard, filling the roles of Arthur and Merlin both, and who had a large happy family to boot. Smaller than the British empire in population if not in size, the inheritance of Prebster John still packs a mighty magical punch. The many kingdoms gathered under John’s rule have mostly joined their identities into a common Christian African identity, whether humans, vampires, dog-headed men (they’re a wide-spread race), or tree men, although Puntland, Alodia, and the Lake Kingdoms as yet retain their local identities, while more backwards recent conquests as yet are still in the process of Christianization and development. Their warriors are valiant and ride elephants, elands, and rhinoceroses, their wizards are powerful (as is often the case with African magicians), their purses very full (John XXIII knows exactly where king Solomon’s gold and diamond mines are), and they have the Ark of the Covenant – although they’re a little reluctant to bring it out of storage: deliberately trying to use it as a weapon may be seen as presumptuous by God, and they’ve already had one bunch of renegade Allmagnian priests and knights show up and try to steal it for the glory of the Empire.
Southern Africa is currently somewhat neglected by Christianity and Islam both, since the Muslims can get where they need to go without rounding the cape and the Christians are blocked from the west coast of Africa by a lot of intervening Muslims. This may change.
Hindu India, it’s inhabitants usually dismissed by idolators by Baghdadis, has been slowly ground down by the Caliphate over the centuries, with OTL Pakistan now directly incorporated and a number of Islamic satellite states established in the North, although some while back a Caliph’s intervention to save a vassal led to a permanent foothold on the west coast. A trio of the larger surviving Hindu states has allied with the Christian (more or less) kingdom of Cochin for defense, but they’re really badly outmatched if the Caliphate really decides to exert itself on the subcontinent: fortunately, the Caliphate is otherwise distracted, for now.
Tibet, whose ruling priesthood is very skilled in the control and taming of various sorts of evil spirits and demons, so far remains unconquered (admittedly, given the desolate nature of the place, the Muslims haven’t tried as hard as they might have).
South China’s Taoist Alchemists may have a surprise or two for Cathay if it tries invasion, while Wa or Cipangu has traditionally had powerful protectors in the form of lines of female shamans, but as the Emperor mourns, there’s never a magical girl around when you need one.
Lying betwixt and between the Islamic and Christian worlds is the Eurasian Alliance, three powers which feel like they’re encircled, denied their place in the sun, etc. Rus’, which received its brand of Christianity from the eastern Romans, strongly disputes Camelot’s claim to the leadership of all Christianity, and desires to prise away both Romelia and Abyssinia from Britain, and its mighty Bogatyrs stand ready to battle the knights of Europe on an even footing (if only there were more of them!). The Khazars, who converted a while back to a form of Judaism (looked upon with some skepticism by the diaspora Jews, which hurts its efforts to recruit Jewish talent from abroad) has no great beef with Christian Europe but needs allies against the Caliphate, and hopes to someday liberate the land of Israel. Both are a little unsure of their mutual ally, the pagan Mongols, who feel they wuz robbed, robbed I tells you, of victory over the Caliphate and Cathay both due to dirty underhanded Islamic magic. (Mongol Shamans are good, but not that good). None are strong enough to challenge the British Empire or the Caliphate on their own: really, even all together they don’t have the numbers or magical might, but at least they look like more trouble than it’s worth to conquer. (The “official line” is a bit more positive: Khan, Czar and King all assure their subjects that yes, together they really are the third *Superpower).
The discovery of the new world has set off a bit of a scramble for souls and land on the part of the Islamic and Christian worlds, which is proving increasingly ruinous to the native *Americans. (It’s the Sinbadi continents in this world). As in the old world, local healers have some genuine magical power, so European/African disease isn’t causing the disastrous depopulation of OTL, but the more developed states and societies are still suffering Black Death and worse levels of casualties, and in this world less developed people are actually worse off, since the sophistication of their mages and healers is usually less. (Both Muslims and Christians are actually trying to help, the Muslims, with their more advanced medical notions, more successfully).
The Islamic conquest is going a bit more slowly than the Spanish one of OTL, in part because the Caliphate is looking for converts and doesn’t consider the locals as disposable as tissue paper, and in part because Mesoamerica and the Andes are quite a bit more politically divided in this time and place:  there is no single great empire to knock over in either are, and the Muslims have to take over eastern Mexico one city-state at a time, with the aid of local allies and converts. The relatively large Mixtec and Zapotec states have joined forces into a (moderately) human-sacrificing alliance of Paganism vs. the forces of the Caliphate and its local allies, but who knows how long that will last. To the north Muslims and Christians are beginning a race to the center of the continent, while Christian missionaries and Knights Errant are messing around in Muslim-claimed South Sinbadia.
Further north, Christian forces have discovered some old enemies: Pagan Norsemen, fleeing the Christian conquest of their homeland, first moved to Iceland, but finding themselves followed by those damn Irish monks, followed the whale-road to Vinland, where they mixed with the local natives and created new Thor and Odin worshipping states, until an alliance of *Huron and Algonquinian peoples stopped their advance inland. Currently, there’s a lot of enthusiasm for a *Crusade to convert them with fire (and the sword), possibly in alliance with the League of the Great Waters, but many suggest that is really a distraction from the _real_ job of kicking the Muslims out of the New Lands altogether, while those with less grandiose vision point out that the League of the Great Waters is pagan too, and perhaps they should ally against them with the Vinlanders, who at least know how to Speak European.
(Christians are a bit rougher on the locals, being more interested in getting them to directly submit to the King-Emperor and Christendom, but there’s no intention of enslaving them all or displacing them, either.)
Horses are only just starting to show up on the Great Plains: as yet the horse-nomad cultures of OTL have not arisen, although some buffalo hunters are getting ideas.
The Americas aren’t as rich in supernatural beings as the Old World, but have their own spirits and monsters, some of which are known to ally with the locals against Christian and Muslim intruders (or against Wotanists. The Little People of the woods really don’t like them, in part due to a number of unpleasant types of Nordic Faye and trolls which followed after them to Vinland ). There aren’t any old-world type dragons, but there are plenty of giant serpents of various types, giants, and shape-shifters, along with such oddities as flying heads or carnivorous hills. There is currently some fierce debate among Islamic scholars whether the fierce deities of Mesoamerica are in any objective sense “real”, and if so whether they are some sort of Djinn, demons, lesser evil spirits, or simply something created through sorcery by the local priests (which the Muslims consider to be powerful black sorcerers).
 Britain, Eire, Asturias, Gaul, Francia, Allemagnia, Italia, Nordland, Romelia, Ungaria
 More than a touch of “Islam with Chinese characteristics.”
 Some of the largest states in the Americas (territorially, at least) are actually Mississippian mound builder kingdoms/federations.
 No dwarfs, though. They really don’t like ocean travel.