they: i.e. the sons of Ephraim.. pre-Exodus raid, presuming perhaps on their descent from Joseph (Genesis 46:20), the governor of Egypt.
Related Commentaries of 1 Chronicles 7:21
1 Chronicles 7:21
21 And Zabad his son, and Shuthelah his son, and Ezer, and Elead, whom the men of Gath that were born in that land slew, because they came down to take away their cattle.