Albert Barnes Commentary 2 Chronicles 21:16

"And Jehovah stirred up against Jehoram the spirit of the Philistines, and of the Arabians that are beside the Ethiopians:" — 2 Chronicles 21:16 (ASV)

The Arabians who were near the Ethiopians — probably Joktanian Arabs from the neighborhood of the Cushites. Southern Arabia was originally occupied by Cushites, or Ethiopians (Genesis 10:7), whose descendants still exist in a remnant of the Himyaritic Arabs.