 The dating system is thought to have originated in the ancient city of Assur, and remained the official dating system in Assyria until the end of the Assyrian Empire in the seventh century BC.The names of the Limmu who became eponyms were originally chosen by lot sortition, until the first millennium it became a fixed rotation of officers headed by the king who constituted the limmu.The earliest known attestations of a year eponyms are at Karum-Kanesh, and became used in other Assyrian colonies in Anatolia.