"American" is a broad term. Taken as meaning North and South America, we simply do not know. There is evidence that tribes from Europe may have arrived here as far back as 100,000 years ago. The Hopi tribe of the North American southwest have a tradition that the first Amerind tribe to migrate here from the north encountered "white" people when they arrived, and systematically wiped them out. There is evidence that the Chinese may have landed on the west coast of North America in the 15th century, and Polynesians may have landed on the west coast of North and South America as far back as 170,000 years ago.