Early civilizations, such as those in egypt, sumer, and harappa, were all

These three civilizations were all centered around rivers that flooded regularly.

Explanation:

In ancient times, to prosper, civilization should be closer to rivers. Most important, it was necessary to understand how the floods work and, then, be adaptative to each situation. In the case of the civilzations that you asked:

a drastic rise in oil prices ended decades of postwar.

while it was true that the cotton gin reduced the labor of removing seeds, it did not reduce the need for slaves to grow and pick the cotton.

explanation:

before eli whitney's invention of the cotton gin, picking and cleaning cotton was a slow, labor-intensive job. workers, usually slaves, had to pick the seeds from the cotton fibers by hand. this invention made it possible to grow large amounts of cotton on big farms and make money.