1 Chronicles 5:7,8

And his brethren The other sons of Reuben, and their posterity. Were the chief Hebrew, the head: each was the head of his family. Who dwelt in Aroer, even, &c. Namely, the Reubenites, all those here before mentioned, as appears, both by the following verses, which relate to the whole tribe, and by the agreement of this description of their inheritance with that Joshua 13:15.