 Later rulers who dominated Assyria and Babylonia occasionally assumed the old Sargonic title "King of Sumer and Akkad", such as Tukulti-Ninurta I of Assyria after c. 1225 BC.Uruk, one of Sumer's largest cities, has been estimated to have had a population of 50,000–80,000 at its height; given the other cities in Sumer, and the large agricultural population, a rough estimate for Sumer's population might be 0.8 million to 1.5 million.The world population at this time has been estimated at about 27 million.