Menes, also known as Aha the Scorpion, is credited with unifying  upper and lower Egypt into one kingdom, thus founding the first Dynasty. Exact evidence of when this took place is sketchy, however it can be estimated as between 3100 and 2850 BC.

 

  Controversy exists as to the true identity of Menes, some evidence suggests that he might be Narmer, based on the discovery of the Narmer Pallete in the 19th century, showing the ruler holding the unified tablets of the upper and lower kingdoms. The possibility exists that they are the same person, or that Narmer: started the process earlier which Menes completed.

 

  Regardless, the ruler is credited for building Memphis, which was made his capitol. The city was strategically located in a defendable location, that could help control the flow of the Nile. This was recorded by Herodotus, of ancient Greece.  To view his writings; http://www.touregypt.net/herodtusmenes.htm