When they discovered these large heads in Mexico in the 19th century it naturally sparked investigations if Africans had sailed to the Western Hemisphere in some distant past long before Columbus.
Most scientists now believe that there was no advanced civilization in the distant past, but some people simply walked across the Bering Straight along with everyone else when the water was lower. There are a number of different kinds of people who live in the borders of present day China.
There is even a group of people who may be a different species
Most of traditional China did not extend as far to the West, and those people are ethnically very different.