Albert Barnes Commentary 1 Kings 15:27

"And Baasha the son of Ahijah, of the house of Issachar, conspired against him; and Baasha smote him at Gibbethon, which belonged to the Philistines; for Nadab and all Israel were laying siege to Gibbethon." — 1 Kings 15:27 (ASV)

Baasha ... of the house of Issachar - It is curious to find Issachar producing a king. Tola, its one very undistinguished judge (Judges 10:1), had immediately settled in the territory of Ephraim upon taking office. The tribe was as obscure as any that could be named. The ass crouching between two burdens was a true symbol of the patient, plodding cultivators of the plain of Esdraelon (Genesis 49:14–15).

Baasha probably owed his rise neither to his tribe nor to his social position, but simply to his audacity, and his known valor and skill as a soldier (1 Kings 16:2).