By the mid-twentieth century, what spread through Africa?

The 20th Century: Africa. ... As the century opened, only two countries in Africa, Ethiopia and Liberia, had independent governments; the rest of the continent was run by European governments and companies. The colonialists came with capitalism, missionaries, teachers and settlers. They came, too, with military force.

Explanation:

the event is known to be the soviet union.

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."