Arabia was a satrapy (province) of the Achaemenid Empire. Achaemenid Arabia corresponded to the lands between Nile Delta (Egypt) and Mesopotamia, later known to Romans as Arabia Petraea, as well as Arabia Deserta and Arabia Felix. According to Herodotus, Cambyses did not subdue the Arabs when he attacked Egypt in 525 BCE. His successor Darius the Great mentions the Arabs in the Behistun inscription from the first years of his reign, and in later texts. This suggests that Darius might have conquered this part of Arabia, or that it was originally part of another province, perhaps Achaemenid Babylonia, but later became its own province.