The weak reign of the last king of Ur, Ibbi-Sin, left space and opportunity for local rulers to establish their own dynasties in Mesopotamia at the end of the third millennium bc. In Isin, Išbi-Erra, one of Ibbi-Sin’s generals, rose to power, and he and his successors saw themselves as the legitimate heirs of the kings of Ur. Sumerian remains the language of the administration and economy and is also employed for most of the royal inscriptions and the extant literature, which is highly reminiscent of court poetry composed for the kings of Ur. The peace and prosperity achieved under the early Isin kings was short-lived, as soon another player joined the political game: the kings of Larsa, who traced back their origins to earlier ancestors than those of Isin. The rulers of the two rival kingdoms took advantage of any weakness in their opponents, and in the first two centuries of the second millennium bc, the size of their territories and their rule over the Mesopotamian cities were in constant flux. The peak of Larsa’s rule is reached with a new dynasty established by Kudur-mabuk, who installed his two sons successively onto the throne of Larsa. The last king of Larsa, Rim-Sin, eventually conquered Isin, and the kingdom of Larsa thus reached its largest extent. Judging from the year names of the second half of his reign, Rim-Sin appears to have rested on his laurels, as no further military activities are recorded. He ended his reign as the prisoner of Hammurabi of Babylon, who conquered Larsa and integrated all its territories into his realm.