The fall of Ur to the Elamites, a pivotal event in Mesopotamian history, occurred around 2004 BCE (middle chronology) or 1940 BCE (short chronology). This event marked the end of the Ur III dynasty and significantly altered the political landscape of ancient Mesopotamia.

The Ur III dynasty, under the rule of King Ibbi-Sin, faced numerous challenges leading to its downfall. The dynasty, which had once controlled a vast empire, was weakened by internal strife, economic troubles, and external threats. A key factor contributing to Ur's vulnerability was the severe famine that plagued the region, compounded by administrative and economic difficulties.

The Elamites, led by King Kindattu of the Shimashki dynasty, capitalized on Ur's weakened state. They launched a military campaign against Ur, successfully besieging the city. The fall of Ur was both dramatic and significant, marked by the sacking of the city and the capture of Ibbi-Sin, who was taken to Elam as a prisoner.

The Elamite conquest of Ur was not just a military victory but also a symbolic one, representing a shift in power from the Sumerians to the Elamites. The Elamites established control over large parts of southern Mesopotamia, imposing their rule and influencing the region's culture and politics.

The aftermath of Ur's fall saw the fragmentation of the region into smaller city-states and kingdoms, such as Isin, Larsa, and Eshnunna, each vying for power and influence in the power vacuum left by the Ur III dynasty's collapse. This period, known as the Isin-Larsa period, was characterized by political instability and frequent conflicts among these states.

The fall of Ur to the Elamites also had significant cultural and societal impacts. It marked the end of the Sumerian city-state model of governance and led to the rise of Amorite influence in the region. The Amorites, a Semitic people, began to establish their own dynasties in various Mesopotamian city-states.