Why would countries ban together to make an embargo?

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.

(202 bc - 220 ad) dynasty started by lui bang; a great and long-lasting rule, it discarded the harsh policies of the qin dynasty and adopted confucian principles; han rulers chose officials who passed the civil service exams rather than birth; it was a time of prosperity