High Egypt and Low Egypt-高埃及和低埃及

At the time of the Ancient Egyptians Egypt was divided in two country: High and Low Egypt. 

The High Egypt enclosed all the Nile's Valley from Assuan to Heliopolis (beside the hodiernal Cairo). The Low Egypt, instead, took up all the area of the Nile's Delta. But why the Egyptians divided their land orientated themselves contrarily? The answer is because they oriented themselves to the geographical south, where the Nile rises ( Victoria Lake, in the center of Africa).