So a thing I've been working on, based on a random shower thought I had: what if, once a language died, ASBs transported some of its major polities to a virgin Earth?
I tried it with Sumerian, because I thought it would be an interesting thought experiment to see a world where the Sumerian Dynastic Period never ended, and the List of Kings kinda went on and on and on and on and on.
So a total of thirteen cities are transported: the five famous prediluvian cities (Eridu, Larsa, Bad-Tibira, Shurupak and Sippar), five important ones integral to Sumeria (Ur, Uruk, Adab, Kish and Akshak), Nippur due to its importance in everything, and three Sumerianate cities abroad (Mari, Hamazi and Awan). Basically - all cities that had a dynasty in the List of Kings before Sargon of Akkad plus Nippur are transported to this new virgin Earth, and the crown once again descends.
The world is now a thousand years into the new political system: While the Third Dynasty of Uruk was soon destroyed by Ur, which continued to rule throughout the period, it gradually weakened as people realised that the other cities were not quite what they looked like, and all but one of the Semitic cities has vanished and stopped giving tribute to Ur. Soon enough, Ur, while surviving, begins to lose influence in the region, to the benefit of Eridu, which is set to regain the crown as the Eriduan nobles determine that the vanishment of everything non-Sumerian is equivalent to a new Great Flood, and that now the Gods what the kingship to return to its original position. This system gradually evolved into Ur's supremacy completely cracking in the region, resulting in the rise of Eridu without it being able to fully topple Ur.
From there, a centenarian dispute arose between the two cities, with the prediluvian cities alligning themselves with Eridu in small city states, while the postdiluvian cities mostly continued to pay tribute to Ur. Eventually a system much like the rivalling leagues in OTL's Greece began to emerge, as Ur and Eridu became increasingly strong and powerful, with competition requiring them to expand beyond Kiengir (Sumer) and into now uninhabited lands. Naval technology was perfected, which led to the creation of small city-states in Arabia (fleeing persecution by the big two); rumors abound of even further colonies, created by the naval power of Kandigir, a small but fundamentally important island-state in OTL's Strait of Hormuz which acts as the middle-man in most stuff. Eventually, with Nippur having fallen out of Ur's hands and becoming a priestly state, nobody had any real claim to the crown: if either Eridu or Ur tried to take Nippur, full-scale war would ensue. Nobody wanted that, and Nippur maintained its uneasy independence, together with the small states of Sumer proper.
With cultures and religions rapidly diverging throughout the centuries as the two countries expanded off their small area, a massive change happened 1500 years or so after the inicial ISOT, when the religion in Ur was reformed and with it politics: the Fifteenth Dynasty of Ur was toppled by peasants, who determined the Kingship had descended once again into the hands of all. A semi-communal system was created in Ur, while Eridu remained ever more stratocratic and religious. The political dispute adquired great religious connotations too.
To the north and east loose federations abound: the diverse cities of Mari, Hamazi and Awan have been the only states to truly expand on their own (not fearing what both Ur and Eridu have determined forbidden kingships of their Gods Utu (in the case of the Iranian Plateau north of Ur), Enlil (in the case of the Arabian peninsula south of Eridu) and Kur (in the case of Egypt)), creating armed federations that are more interested in outward expansion than in Sumerian affairs. Technological progress outside of Kandigir is slow and painful, while languages have diverged in such a way that the Sumerian language family is now composed of hundreds of individual languages with barely any mutual intelligibility outside of the initial territories of Sumer (Kandigir and the South Arabian states have especially diverged from Sumerian over the centuries.
(For this map I tried to do the National Geographic-style boundaries with the colours instead of just black lines but I'm not sure it really did work out that well. What do you guys think?)