Hor-Aha succeeded Narmer as ruler of both Upper and Lower Egypt, so it is assumed that Narmer was his father. Hor-Aha continued the process of unifying Egypt into a single kingdom. His big contribution was the founding of the capital city at Memphis, a site that was located between Upper and Lower Egypt. At one point, Hor-Aha's army raided the Nubians in the south, spreading his rule as far down as the first cataract of the Nile. He reigned for over 60 years, until he was killed by a hippopotamus (although some sources say it was actually a crocodile that did him in).