Why was sub saharan africa so far behind technologically

Explanation:

They have not fully developed yet. It doesnt help that their population grows larger in less than a year. They may not be able to afford such technologys because they are fulfilling the needs of their people.

2686-2181 bce-- "egyptian civilization developed along the nile river in large part because the river’s annual flooding ensured reliable, rich soil for growing crops."

1069-664 bce-- "ancient egyptians developed wide-reaching trade networks along the nile, in the red sea, and in the near east."