Adam Clarke on Jeremiah 46:9

The Ethiopians - Hebrews Cush, Phut, and the Ludim. This army was composed of many nations. Cush. which we translate Ethiopians, almost invariably means the Arabians; and here, those Arabs that bordered on Egypt near the Red Sea. Phut probably means the Libyans; for Phut settled in Libya, according to Josephus. Phut and Cush were two of the sons of Ham, and brothers to Mitsraim, the father of the Egyptians, Gen 10:6; and the Ludim were descended from Mitsraim; see Gen 10:13. Bochart contends that the Ludim were Ethiopians, and that they were famous for the use of the bow. Phaleg, lib. 4:26.