Aswan — the frontier town in the river.

Elephantine sat at Egypt's southern border, the customs post and garrison controlling trade with Nubia through the First Cataract. Its nilometer measured the flood that set the year's taxes. The island holds a temple of Khnum, the ram-headed god believed to control the inundation from caverns beneath it, and the remains of a Jewish garrison community of the fifth century BC known from its surviving Aramaic papyri.