Identify ALL of the people, events, or movements from the 1960’s

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

explanation:

i think that this is the best answer, but im sorry if this is wrong

the answer is a) high entry costs