Irkabtum is referred to in an old
Hittite letter fragment, but he is known primarily through the
Alalakh tablets. He engaged in the selling and buying of cities and villages with his vassal king
Ammitakum of Alalakh in order to adjust the shared borders between them, and he campaigned in the region of Nashtarbi east of the
Euphrates River, against the Hurrian princes who rebelled against Yamhad. The campaign was an important one in that it was used to date legal cases. Irkabtum is known to have concluded a peace treaty with Semuma, the king of the
Habiru, on behalf of his vassal kingdom Alalakh, indicating the importance and danger of those autonomous warriors in the region. ==Death and succession==