The city became a political force during the Isin-Larsa period. After the Third Dynasty of Ur collapsed c. 2000 BC, Ishbi-Erra, an official of Ibbi-Sin, the last king of the Ur III Dynasty, relocated to Isin and set up a government which purported to be the successor to the Ur III dynasty. From there, Ishbi-Erra recaptured Ur as well as the cities of Uruk and Lagash, which Larsa was subject to. Subsequent Isin rulers appointed governors to rule over Larsa; one such governor was an Amorite named Gungunum. He eventually broke with Isin and established an independent dynasty in Larsa. To legitimize his rule and deliver a blow to Isin, Gungunum captured the city of Ur. As the region of Larsa was the main center of trade via the Persian Gulf, Isin lost an enormously profitable trade route, as well as a city with much cultic significance.