John Gill Commentary 1 Chronicles 5:8

"and Bela the son of Azaz, the son of Shema, the son of Joel, who dwelt in Aroer, even unto Nebo and Baal-meon:" — 1 Chronicles 5:8 (ASV)

And Bela the son of Azaz, the son of Shema, the son of Joel ,
&c.] The pedigree of Bela, another principal man in the tribe of Reuben, is traced up to Joel the father of Shema; the same with Shemaiah, according to Kimchi and Ben Melech, (1 Chronicles 5:4)

who dwelt in Aroer ;
which belonged to the tribe of Gad, and was rebuilt by them, (Numbers 32:34) wherefore Kimchi observes, it may be interpreted, either from Aroer, or on the border of it, Bela dwelt:

even unto Nebo, and Baalmeon; of which (See Gill on Numbers 32:38).