In the mid-22nd century BC, the Akkadian Empire collapsed under circumstances that remain unclear. The Gutians are generally considered the primary agents of its downfall, though at the same time Lower Mesopotamia fragmented into several independent city-based kingdoms, especially Uruk and Lagash, the latter ruled by the prominent king Gudea. Meanwhile, a strong state also emerged in Elam under Puzur-Inshushinak.
Around 2120–2055 BC, Utu-hegal of Uruk defeated the Gutian king Tirigan and established dominance over southern Mesopotamia. However, his rule was brief. After roughly eight years, he was overthrown by court elites led by Ur-Namma, the governor of Ur - likely his brother. Mesopotamian tradition regards Ur-Namma as the founder of the Third Dynasty of Ur.
Under his rule, a highly organized and prosperous agricultural and urban society developed, supported by an advanced administrative system centered on temple estates under royal control. Military campaigns further extended Ur’s influence, effectively forming an empire. Ur-Namma’s successor, Shulgi, and the rulers who followed managed to sustain this empire for about 25 years. Eventually, it declined due to a combination of Amorite incursions from the north and internal fragmentation, as major cities and regions regained independence. The kingdom of Ur ultimately fell around 2004 BC after an invasion by Elamite forces.