The city-state of Ashur was the capital of Assyria. Ashur was founded in 1900 B.C. as an oligarchical city-state that developed merchant colonies in Cappadocia.
Shamshi-Adad conquered Ashur and made it his capital city as he continued to conquer the areas around it in Mesopotamia, making Assyria one of the greatest empires in the area. Ancient Assyria covered the vast majority of northern Mesopotamia. King Hammurabi of Babylon conquered Assyria after Shamshi-Adad's death, which made Assyria a vassal state. When Ashur-uballit I seized the throne of Assyria in the 14th century B.C., he conquered Babylon, returning the capital to Ashur.