Answer:
The Great Migration was the movement of some six million African Americans from rural areas of the Southern states of the United States to urban areas in the Northern states between 1916 and 1970.
Explanation:
I am not sure, but I believe it is the Qin Dynasty
Answer: There were many obstacles
Explanation:
They abandoned the nomadic life by developing farming techniques through water management, including canal-building, water storag, drainage, irrigation.
With the prosperity which this generated, they moved on to development of almost all the techniques that formed the basis of civilized life before the industrial revolution: architecture, transport, metalworking, carpentry, pottery, glass-making, textile manufacture and leather-working as well as many processes associated with farming and food preparation. In southern Mesopotamia irrigation and flood control were necessary and this gave rise to a number of subsidiary technologies of
