They fought against the Hagrites and the tribes of Jetur, Naphish, and Nodab.
Hadad, Tema, Jetur, Naphish, and Kedemah.
(SEE 1:29)
These were the men in charge of David's royal property.
When Saul was king, the Reuben tribe attacked and defeated the Hagrites, then took over their land east of Gilead.