by Shulgi, the greatest king of the Third Dynasty of Ur, who solidified the hegemony of Ur and reformed the empire into a highly centralized bureaucratic state. Shulgi ruled for a long time (at least 42 years) and deified himself halfway through his rule. The Ur empire continued through the reigns of three more kings with Semitic Akkadian names, Amar-Sin, Shu-Sin, and Ibbi-Sin. It fell around 1940 BC to the Elamites in the 24th regnal year of Ibbi-Sin, an event commemorated by the Lament for Ur. According to one estimate, Ur was the largest city in the world from c. 2030 to 1980 BC. Its population was approximately 65,000 (or 0.1 per cent share of global population then). The city of Ur lost its political power after the demise of the Third Dynasty of Ur. Nevertheless, its important position which kept on providing access to the Persian Gulf ensured the ongoing economic importance of the city during the second millennium BC. The city came to be ruled by the first dynasty (Amorite) of Babylon which rose to prominence in southern Mesopotamia in the 19th century BC. After the fall of Hammurabi's short lived Babylonian Empire, it later became a part of the Sealand Dynasty for several centuries. It then came under the control of the Kassites in the 16th century BC. Iron Age The city, along with the rest of southern Mesopotamia and much of the Near East, Asia Minor, North Africa and southern Caucasus, fell to the north Mesopotamian Neo-Assyrian Empire from the 10th to late 7th centuries BC. From the end of the 7th century BC Ur was ruled by the so-called Chaldean Dynasty of Babylon. In the 6th century BC there was new construction in Ur under the rule of Nebuchadnezzar II of Babylon. The last Babylonian king, Nabonidus (who was Assyrian-born and not a Chaldean), improved the ziggurat. However, the city started to decline from around 530 BC after Babylonia fell to the Persian Achaemenid Empire, and was no longer inhabited by the early 5th century BC. The demise of Ur was perhaps owing to drought, changing river patterns, and the silting of the outlet to the Persian Gulf. Identification with the Biblical Ur Ur is possibly the city of Ur Kasdim mentioned in the Book of Genesis as the birthplace of the Hebrew and Muslim patriarch Abraham (Ibrahim in Arabic), traditionally believed to have lived