Herodotus mentioned an invasion of Kush by the Achaemenid ruler Cambyses (c. 530 BC), who possibly succeeded in occupying the area between the first and second Nile cataract.[41] Achaemenid inscriptions from both Egypt and Iran include Kush as part of the Achaemenid empire.[42] For example, the DNa inscription of Darius I (r. 522–486 BC) on his tomb at Naqsh-e Rustam mentions Kūšīyā (Old Persian cuneiform: 𐎤𐎢𐏁𐎡𐎹𐎠, pronounced Kūshīyā) among the territories being "ruled over" by the Achaemenid Empire.[43][42] Archaeological evidence suggests that the fortress of Dorginarti near the second cataract served as Persia's southern boundary.[44]