Qinhuangdao and Qingdao are two separate cities 440 km apart. One is in Shandong province while the city in the answer is in Hebei Province. Also the qing in Qingdao does not reference the dynasty but a color shade similar to aqua.
I would change the wording on the clue for Columbus, as the general consensus is that he did not discover North America. The Native Americans, including all groups that migrated to the continent, found it first, and then Leif Erikson and possibly even other explorers found it, all before Columbus arrived.