Albert Barnes Commentary 2 Chronicles 12:3

"with twelve hundred chariots, and threescore thousand horsemen. And the people were without number that came with him out of Egypt: the Lubim, the Sukkiim, and the Ethiopians." — 2 Chronicles 12:3 (ASV)

twelve hundred chariots - This number is not unusual (1 Kings 10:26). Benhadad brought 1,200 chariots into the field against Shalmaneser II, and Ahab had a force of 2,000 chariots at the same time (compare the 1 Kings 20:1 note).

The Lubim, or “Libyans” (Daniel 11:43), were a people of Africa, distinct from the Egyptians and the Ethiopians dwelling in their immediate neighborhood. They were called Ribu or Libu by the Egyptians .

Sukkiim - This name does not occur elsewhere. The Septuagint, which rendered the word “Troglodytes,” probably regarded the Sukkiim as the “cave-dwellers” along the western shore of the Red Sea. However, the conjecture that the word means “tent-dwellers” is plausible and would point instead to a tribe of Arabs (Scenitae).