In 2 Kings 3:4 we read that Mesha, king of Moab, was required to give a tribute of sheep and wool. Most likely David expected and received a similar tribute from the Moabites. In the ancient Near East, tribute typically included valuable goods such as gold, silver, bronze, livestock, and other agricultural products.
2 And he defeated Moab and he measured them with a line, making them lie down on the ground. Two lines he measured to be put to death, and one full line to be spared. And the Moabites became servants to David and brought tribute.