Although Sumu-Epuh's early life or the way he ascended the throne is not known, he is considered the first king of Yamhad, and his realm included Alalakh and Tuba.
[4] Yahdun-Lim was an ambitious ruler who campaigned in the north claiming to have reached the Mediterranean, in spite of having a dynastic alliance with Yamhad to oppose Assyria.
[5] Those campaigns caused Sumu-Epuh to support the Yaminite tribes centered at Tuttul against the Mariote king,[6][7] who emerged victorious but was soon killed by his own son.
Sumu-Epuh aided by Khashshum attacked a kingdom in Zalmakum (a marshy region between the Euphrates and lower Balikh).
[11] Sumu-Epuh apparently was killed in c. 1780 BC during his fight with Shamshi-Adad,[7] His successor was Yarim-Lim I, his son by his queen Sumunna-Abi.