It is the year 1679 by the Christian calendar, and 1090 by the Islamic one, which is the more important on this Muslim-dominated world, where an early scientific revolution and more stable Abbasid succession (combined with a superior system of military control which kept the Caliphs from becoming puppets of their own guards) gave the Islamic world an edge in the world-dominance stakes it has never lost.
The universal Caliphate is long gone, and "Caliph" now simply means the executive position in a sovereign state, sometimes elective (usually for life) or hereditary, although the title is restricted to the rulers of major powers and the rulers of minor states which adopt the title are considered rather laughable. There are currently seven "true" Caliphs, five Muslim, one Christian and the Chinese one, who is usually Buddhist, a Chinese religious "traditionalist", or a combination thereof. (Hind, BTW, has been using political shenanigans to keep the government Muslim-dominated, but there will probably be a Hindu Caliph one of these days). Rum isn't really considered one of the Big Boys, and there are a couple other "point and laugh" Caliphs, although Takrur still is a sizable chunk of the globe. The global independent judiciary or "Ulamah", which in spite of it's Shari'a based origins is nowadays mostly secular, stands to some extent above all powers, although dependent on Sultans and Caliphs for enforcement.
Technological and industrial progress, in spite of some precocious developments of machinery powered by steam boiled by petroleum, has lagged compared to pure scientific understanding, given that the 9th and 10th century Middle East had some disadvantages compared to 17th century western Europe (a lack of coal and iron, thin populations, limited agricultural land, underdeveloped capitalism and a lack of security in property, lack of centuries of incremental scientific progress, etc...). This did allow Christianity to rally under the Holy Roman Emperors in time to avoid total extinction, and at time made things difficult for scientists themselves when they found themselves lacking the authority conferred by, say, locomotives and telegraphs, when introducing revolutionary ideas (evolution only became publicly palatable on the third try to introduce it).
Still, after some eight centuries of progress, things are well ahead of OTL technologically. Tens of millions of people live off-planet on various space habitats, moons, planets and asteroids of the solar system. Glittering synthetic-diamond skinned towers reach a mile high above the great cities. Antimatter-powered probes have been sent to other stars, although none have reached them yet (the interesting looking planets, alas, are quite some ways away) except the "proof of concept" probe sent to Alpha Centauri, a favorite destination of old-tyme SF writers in this world as in ours. Robots do the manufacturing, and society is to some extent post-scarcity, even in more backward areas like China or some parts of interior Africa or the Americas: although production isn't enough to make everyone _wealthy_, nobody need go without food, basic shelter, education, or the equivalent of internet access. Corporations, of course, as OTL work to make people think that living in anything less than luxury is shameful.
Lifespans have been considerably extended, to the point where laws have been passed forcing people to retire at 100 to prevent excessive concentration of power and wealth among the elderly. True AI remains elusive, but computers have become quite good at faking sapience. Limbs and organs can be cloned for replacement, and although cybernetic limbs are possible, they are usually considered just temporary replacements until the organic limb is possible: being visibly cyborged is considered full-body-tattoo weird on Earth, although brain implants to link directly to computer systems are gaining popularity among the young. Genetic engineering exists, but is confined to animals and plants: aside from prenatal screening, human genetic engineering is illegal anywhere on Earth.
The world is at peace, and has been so for a while. It has been almost three centuries since the last true global big-power war, and a century since _any_ interstate conflict on Earth (although there have been some internal rumblings within states, and occasionally idiotic conflicts break out between the various hothouse cultures of the Belt, the solar system's great fruitcake reserve). Racism is largely unknown, although the association of East Asians with "heathenism" tends to give them a tinge of scary exoticism to Muslims in other parts of the world.
All is not perfection, though. Many chafe under the technological restraints imposed by the global legal system or Ulamah and enforced by the Caliphates. Some feel this has prevented the development of true immortality, or the creation of better human beings through genetic engineering. Others dislike the present economic system, which they feel is manipulated by the powerful to prevent universal wealth and concentrates power in too few hands. There is the limited social mobility, the crushing power of entrenched custom and expectations, and in places like India the placing of people in little cages shaped by which of hundreds of sub-cultures you belong to. There are angry feminists, who are deeply frustrated by the fact that although long equal under the law men and women remain socially segregated and women are often informally blackballed from a number of professions (there are no female Caliphs). People who want to exist outside of historical gender roles altogether are considered weird, and homosexuality although accepted is not meant to be flamboyant. The Ummah, which supposedly represents a new freedom from government constraints, is to many simply the replacement of top-down tyranny with local petty authoritarians, with inadequate social services either paid for with inadequate antique taxation systems or provided - at a cost - by private institutions, and even lower social mobility than in the Caliphates. Religious discrimination remains widespread, and while legal restrictions are rare nowadays, Christians and Jews are essentially second-rate citizens in many Muslim countries (indeed, Jews are disadvantaged everywhere on Earth,  which is why there are now over a million Jews! In! Spaaaace!), and "heathens" (Hindus, Buddhists, etc.) are oddballs everywhere outside their own countries, while outspoken atheists are considered loonies of the most annoying sort. (Muslims, being Top Dogs, avoid open discrimination everywhere, but in places like China there is a lot of secret spitting in the soup and so on).
Against the rather stultifying Way Things Are stands the complex and diverse Jamahiriya, a global movement (if strongest by far in Talentis/the Americas), which want a genuinely secular society, an overthrow of old cultural and social restrictions, in many cases a scientific socialist economy (given robotic manufacturing, fusion power, and supercomputers, probably actually achievable with a boost to lower class living standards to boot), an end to traditional roles of gender and sex and lifestyles, an end to limitations on technological progress. The more extreme post-humanists tend to squick out other members of the movement, but it is true that the notion of Men Like Gods is not without its mass appeal. And then there are those who are just annoyed by the excessively flowery, polite and melodramatic language in what passes for "society" nowadays...
It was 1090 AH, and war was coming.
 Islam has always been pro-merchant, and although there has traditionally been top-down public aid of various sorts, the notion of a socialistic _society_ has remained a fringe proposition. On the other hand, so has Ayn Rand type take-no-prisoners libertarianism, so you win some, you lose some.
 Theoretically they should be OK in China and other Buddhist countries, but the locals tend to look suspiciously at Jews because looking suspiciously at Jews is what all the cool kids do.