Lord of the land of Massi, then raised to the rank of king of the land of the Mannaeans by Sargon II. Ullusunnu was the son of Iranzu and the brother of Izâ, whom he succeeded after his tragic death in 716 at the battle of Mount Wa'ush (Wa'uš). As a vassal, Ullusunnu was vulnerable to constant pressure from Urartu and its allies. One of the aims of the 714 campaign was to provide him with military support. He was symbolically reinstated at the head of the land of the Mannaeans at the Sirdakka banquet and his son was sent to Assyria to be raised there.