Judges 10:8

And that year, when the Lord first delivered Israel into their hands, they vexed and oppressed, broke and crushed, the children of Israel, but that was merely the beginning of the punishment; eighteen years, all the children of Israel that were on the other side Jordan in the land of the Amorites, which is in Gilead. So the two and one half tribes were the chief sufferers in this oppression at the hands of the children of Ammon.