Because even though there are Pyramid complexes throughout Sudan (Nubia) the Delta (lower Egypt) is where the flooding occured most and in turn was the area where agricultural production and farming was based and the Giza complex and Sphinx were astronomical markers pointing to the Sirius cycle thus they knew when the inundation was coming based on the poistions of Sirius and Sothis.
I always thought it meant more than that. I find it interesting that the Nile river is the main river for the central parts of Africa. The Congo river is in the lower parts of Central Africa but it only flows in Central Africa. Where as if population is to increase in those parts, getting out of the central part is essential. I always thought that not only did the Pyramids represent all that you stated, but that the pyramids at the
top of Egypt was symbolic to
all Africans of like mind, who joined forces to bring Egypt to where it was. Hence all Africans migrated up to Egypt and that is why Egyptians look like different Africans because they infact are a combination of Africans.
Pyramids represent building, migration, unity, everyone on the bottom pushing each other out from the top and the cycle goes on....
The pyramid scam that came outsome time back, would work
properly if people understood what the pyramid it self, represents...
The Zambezi and Limpopo river are located in the South, and they only flow in the South. The Niger river is in the West, and it only flows in the West. So I am thinking that with the Nile river being the only River that stretches from the Central east
( the cradle of civilization, a recognized meeting up point for Africans) into the Northern part of Africa, when Africans discovered this, they set up shop and built the pyramids not only for all the reasons you wrote, but also to show how civilizaion in Egypt came about. The Blue Nile located in East Africa flows into the White Nile so I didn't mention the Blue Nile.
Any way, Egypt didn't come about due to one kind of African, Egypt became what it was due to like minded Africans that migrated... If you follow the water or delta breeze, from Central Africa into no doubt the South, to the West and then the North where they made discoveries unlike before not limited to, such as those you mentioned.
I imagine that before Like minded Africans decided to migrate to Upper Egypt, other Africans had already been there and came back to lower Egypt to inform other Africans to all benefits of Egypt. I don't think they would call it upper Egypt and Lower Egypt had not it been the lower Egyptians ( West Africans, south Africans, Central Africans, one in the same) who migrated to upper Egypt, where the pyramids were built to also represent Unity.
Astrologer4U