Albert Barnes Commentary 1 Kings 16:22

"But the people that followed Omri prevailed against the people that followed Tibni the son of Ginath: so Tibni died, and Omri reigned." — 1 Kings 16:22 (ASV)

A comparison of the dates in 1 Kings 16:15, 1 Kings 16:23, and 1 Kings 16:29 shows that the contest between the two contenders lasted four years.

Tibni’s death is unlikely to have been natural. He must have either been slain in battle against Omri or been captured and put to death.

There has likely been some rearrangement of the text here. The passage may have originally read: “So Tibni died, and Omri reigned in the thirty-first year of Asa, king of Judah. Omri reigned over Israel twelve years; he reigned six years in Tirzah.” Omri’s twelve-year reign began in the 27th year of Asa’s reign (1 Kings 16:15–16) and ended in his 38th year (1 Kings 16:29). The event belonging to Asa’s 31st year was the death of Tibni and the resulting extension of Omri’s kingdom.

The six years in Tirzah are probably composed of the four years of conflict with Tibni and two years afterward, during which enough of Samaria was built for the king to move his residence there.