Until 1880, America had a policy by which unlimited numbers of people from around the world could enter this country legally with few exceptions. WHat was the name of this policy?

the mongolian invasion of china and central asia resulted in a disruption of the silk road as the chinese garrisons lost support from the chinese kingdoms which fell under the mongols. however, as the mongols established a formal dynasty in china, the successors of genghis khan restored the garrisons along the silk road allowing the safe travel caravans again.

d. the great plains       hop3 this yo

bye cutting off more workers so the graph can go back up