This is based on the GURPS Infinite Worlds "Nergal" scenario, sans the black magic and interdimensional interventions.
In this world the Neo-Assyrians did rather better, crushing the Babylonians for good and all, knocking the Medes and Scythians back east, and incidentally wiping out the Jews and annihilating the independence of the Phoenician cities when they got uppity. (In the process preventing Monotheism from catching on and keeping most writing systems complex and literate-elite dependent). The Empire fell in time, as all empires do, but lasted long enough and extended far enough that it became, like the Romans OTL, the model for later Empires to emulate. Rome was butterflied, Carthage was never founded, and while Greece was not destroyed, being a bit on the fringes of Assyrian power, it was pillaged and raided enough to traumatize the heck out of the Greeks and send their development off in other directions: the eventual Greek Empire, of Italy, the Balkans up to the Danube, western Anatolia and (briefly) Syria and Egypt was a nasty enough piece of work that few mourned it's passing.
The current sixth Assyrian empire isn't really Assyrian anymore (it's creators were an Arab-derived people) but it seeks very energetically to emulate its predecessors. Human sacrifice (adopted, unlike the Alphabet, from the Phoenicians) takes place at the massive basalt and granite ziggurats at regular intervals (if not on the same scale as the MesoAmericans) and the guts of the sacrifices inspected for important omens. Energetic cultural assimilation is pushed hard, with mass population transfers only one mechanism: the Armenians have largely been wiped out as a separate people, and the Greeks survive as scattered pockets in rugged locations (Egypt remains a Problem). Warfare and expansion are pursued as the most important way for a king to maintain prestige, and current aims are to take all of *Italy from the Celtic Nerwa and secure the *Sind as a base for further expansion into India.
Human sacrifice, severe inequality, and frequent warfare are the norm of this world. Technology is late medieval and superstition rank. Cannon and gunpowder haven't been invented yet, although Celtic distillers have led to the invention of the Molotov Cocktail, the oil-rich Assyrians have a variety of spins on the Greek Fire concept, and the *Korean Taehanese have developed an interesting concept involving a partially evacuated chamber and very fine coal dust, which if successfully deployed does one hell of a job on the walls of besieged cities.
No gunpowder, you ask? The Chinese were hit by waves of Iranic invaders, starting with Sogdians knocked east, before the Warring State militarization had peaked, and the development of Sinic culture was rather disrupted: the current *Chinese are divided into multiple states, have an aristocratic and rather feudal social system, and aren't that big on scholarship, although their art and architecture is pretty gorgeous, as are the banquets at which captured elite enemies are ritually eaten. (Peasants are only _rarely_ eaten: after all, who knows what diseases they may be carrying?) They haven't invented paper either, although some Indians did invent printing.
Tamil south India is one of the more civilized parts of the globe: true, widows still burn to death, untouchables are still treated like crap, the rich oppress the poor, etc., but human sacrifice (aside from a certain amount of unofficial work on the part of the disciples of Kali Ma) is unknown, and there is enough of a balance of power between priesthood, kings, nobles and rich merchants that there is a fair amount of security of life and property for most of the population. Now as long as the Northerners don't successfully invade, exterminate the nobility, and convert a third of the remaining population into a dozen new sub-castes of Untouchable, things will be fine. (The Tamils are understandably cheering the Assyrians on).
The Americas have recently been discovered by *Europeans, and the native civilizations are probably screwed, although the Celts and Northmen are less crusade-minded and probably a bit cleaner than 16th century Europeans. (The Celts and Germanic peoples, after centuries of war and trade and God-swapping have come to see eachother as Fellow Warriors and get along fairly well nowadays, although the Germans still think of the Celts as bloody-minded putzes who couldn't organize an orgy in a whorehouse, while the Celts think of the Germans as anal-retentive perpetual downers with absolutely no taste in facial hair).
With no Romans or Carthaginians, the NW African coast passed through the hands of various peoples, Greeks, Egyptians, Celtic adventurers, etc. until some 700 years ago when Wiwurgh The Bloody-Handed came out of the mountains to found the first universal Berber Empire. Things have gone up and down in the interval, and the Celts briefly conquered much of the area during a period of disunity, but currently the area is united under a new dynasty which currently holds the strategic region of the straits. Not much for messing about in boats, the Berbers haven't made any conquests in the Americas, and in any event keeping at bay the Assyrians is the most important foreign policy objective.
Locals are a bit worried about the weather: the sun is currently in a solar minimum, and winters are colder than usual. Harvests have been poor in northern latitudes, and unrest has resulted. The complex fluctuations of sun, moon and Earth may in fact bring on a new ice age in a world with little burning of coal, and it may be up to the technologically precocious Bantu of South Africa to get the Age of Greenhouse Gasses going...