Ashur-uballit I (Aššur-uballiṭ I), who reigned between 1365 and 1330 BC, was the first king of the Middle Assyrian Empire (1365–1050 BC). After his father Eriba-Adad I (1392-1366 BC) had broken Mitanni influence over Assyria, Ashur-uballit I's defeat of the Mitanni king Shuttarna II marks Assyria's ascendancy over the Hurri-Mitanni Empire, and the beginning of its emergence as a powerful empire. Later on, due to disorder in Babylonia following the death of the Kassite king Burnaburiash II, Ashur-uballit established Kurigalzu II on the Babylonian throne, in the first of what would become a series of Assyrian interventions in Babylonian affairs.
From the Amarna letters, a series of diplomatic letters from various Middle Eastern monarchs to Amenhotep III and Akhenaten of Egypt, we find two letters from Ashur-uballit I, the second being a follow-up letter to the first. In the letters, Ashur-uballit refers to his second predecessor Ashur-nadin-ahhe II as his "father" or "ancestor," rather than his actual father, Eriba-Adad I, which has led some critics of conventional Egyptian chronology, such as David Rohl, to claim that the Ashur-uballit of the Amarna letters was not the same as Ashur-uballit I. This, however, ignores the fact that monarchs in the Amarna letters frequently refer to predecessors as their "father," even if they were not their biological sons. In this case, Ashur-uballit presumably referred to Ashur-nadin-ahhe because the latter, unlike Eriba-Adad I, had previously corresponded with the Egyptian court.
With Assyrian power firmly established, Ashur-uballit started to make contacts with other great nations. His messages to the Egyptians angered his Babylonian neighbour Burnaburiash II, who himself wrote to the Pharaoh: “with regard to my Assyrian vassals, it was not I who sent them to you. Why did they go to your country without proper authority? If you are loyal to me they will not negotiate any business. Send them to me empty-handed!”