Achaemenid religious policy toward conquered peoples was not uniform, and the empire's dealings with Egypt show both its harsher and more accommodating faces within a single conquest. Cambyses II conquered Egypt in 525 BCE, and later Greek and Egyptian sources accused him of killing the sacred Apis bull and desecrating Egyptian temples, a reputation for sacrilege that colored Greek writing about Persia for generations afterward, whatever its exact basis in fact.
Darius I, who took the Achaemenid throne a few years later, pursued a markedly different course in Egypt. A history of Egypt covering the Persian conquest describes Darius restoring damaged temples, commissioning new temple construction dedicated to Egyptian gods, and having himself depicted in Egyptian temple reliefs in the traditional regalia of a pharaoh making offerings to Egyptian deities, adopting the religious language of the people he ruled rather than imposing Persian religious forms on them. Darius's Egyptian temple patronage sits alongside the more famous Achaemenid policy toward the Judean exiles as evidence that the empire's approach to subject religions was calculated province by province, aimed at securing the cooperation of local priesthoods rather than following any single imperial religious doctrine.