Albert Barnes Commentary 2 Kings 10:36

"And the time that Jehu reigned over Israel in Samaria was twenty and eight years." — 2 Kings 10:36 (ASV)

In Samaria - The family of Ahab had made Jezreel a sort of second capital and had reigned there, at least in part (2 Kings 9:15–30). Jehu and his descendants seem to have fixed their residence wholly in Samaria (2 Kings 13:1, 10; 2 Kings 14:23; 2 Kings 15:8).