He was the god of the eastern frontier of Egypt, of the desert tracks that led from the Delta out through the Wadi Tumilat toward the Sinai and the Red Sea. The eastern desert was a place of mines and of nomads, of the turquoise of Serabit el-Khadim and the copper of Wadi Maghara, of caravan routes and military expeditions; and over all that landscape Sopdu was the watchful god, falcon-headed and hawk-eyed, who saw the king's enemies before they could approach.

He bore the title 'Lord of the East,' and his cult-center was at Per-Sopdu in the eastern Delta, near the modern Saft el-Hinna. He was depicted in two principal forms: as a falcon-headed man with two long plumes upon his head, holding a was-scepter, in his guise of the divine warrior; and as a crouching falcon mummiform, in his guise of the celestial body identified with the morning star or sometimes with Orion. He was reckoned the consort of Sopdet by some traditions, the father of Sopd the morning star, and an ancient guardian of the eastern boundary of the kingdom.

In the campaigns of the New Kingdom into the Sinai and the Levant, Sopdu was invoked as the god who went before the army; the great king Senusret III was depicted offering to him before setting out on his expeditions, and the inscriptions of Hatshepsut at Punt include him among the gods of the eastern lands. He persisted through the Roman period as a god of the frontier, and small bronzes of him in his falcon-mummiform are well attested in the votive deposits of the eastern Delta.