It was at the boundary between Lower and Middle Egypt, where the river craft paid tolls when ascending or descending the Nile. Diodorus ascribes the erection of the first fort to rebel Assyrian captives in the reign of Sesostris, and Ctesias (Persica) dates it to the time of Semiramis; but Josephus (l. c.), with greater probability, attributes its structure to some Babylonian followers of Cambyses, in 525 BC. The Romans built a new fortress with typically Roman red and white banded masonry nearer to the river.