1 Chronicles 5:9-10

9Their east border was the desert that goes all the way to the Euphrates River. They had too many animals to feed in the region of Gilead. So they had to live in all those other places too.

10When Saul was Israel's king, the men of Reuben's tribe attacked the Hagrites. They won the fight. Then they moved into their land to live. That was the whole region that was east of Gilead.