Why did Ur decline as a city-state

The Third Dynasty of Ur, also known as theNeo-Sumerian Empire or the Ur III Empire, refers simultaneously toa 21st to 20th century BC Sumerian ruling dynasty based in the cityof Ur and a short-lived territorial-political state that somehistorians regard as a nascent empire. Ur was a major city, andlater the capital, of the Sumerian Empire in southern Mesopotamia.Its location near the sea made it a center of commerce and traderoutes. Between 2030-1980 BCE, Ur was the world’s largest city,boasting about 65,000 inhabitants within its walls. The cityfeatured many glorious temples and tombs. Today, the site isrecognizable for its well-preserved remains of the GreatZiggurat.