The first 300 years of the second millennium B.C. mark the height of Dilmun’s prosperity and the greatest geographical expansion of its culture. The island of Failaka is settled soon after 2000 B.C. Trade along the Gulf declines following unrest in Mesopotamia with the collapse of Hammurabi’s kingdom and the Indus Valley civilization. Sources of copper from Anatolia and Cyprus now undercut Gulf supplies to Mesopotamia. From around 1500 B.C., the Kassite rulers of Babylonia extend their power along the Gulf—a governor is established on Bahrain (his official correspondence is found at Nippur). In 1225 B.C., the Kassites are defeated by the Assyrian king Tukulti-Ninurta I, who takes the title “king of Dilmun and Meluhha.”