His father Hadram ruled from the city of Arne (Tell Aran), which is the largest archaeological mound in the Aleppo region of Syria.
Arne was first inhabited by the Arameans, and served as the first royal capital of the Aramaean kingdom of Bit Agusi.
In 849 BC, Hadram joined an uprising against Assyria participating in an alliance with Sangara, the king of Carchemish, and other local rulers.
Atarshumki tried to build a coalition with his neighbors against the Assyrians; finally, in 796, Adad-nirari III launched a military campaign in the area, and subjugated it.
The reason for preferring Arpad is clear: it had broken up the lines of the Syro-Hittite coalition, and opened before Adad-nirari III the way to the south, to Damascus.