43,000 marchers, including 17,000 WWI veterans, their families and supporters marched on Washington in 1932. They were known as the Bonus Army
The use of robots and how they help build cars and how the assembly line has improved from the 1900's would be my answer.
Answer: Mandate of Heaven
That's a hard one to answer but from all my reading it would seem there was one main reason. The Berbers were nomads so they never were able to be collectively together to form an army against invaders. Therefore, the Berbers were constantly being conquered by someone. Each time they had to learn new laws set out by the conquerors. When the Arabs came with their mighty army, they knew they couldn't fight so giving in was in an odd way a protection system of kinds.
Fish first then Apes then Humans