What evidence is there that about one-third of cowboys were non-white?

Approximately one-third of cowboys in the American  

West were nonwhite, the largest group being  Mexican vaqueros

African Americans comprised the second-largest

group of nonwhite cowboy

Explanation:

2. a land bridge connected asia and north america thousands of years ago.

4. crossing the land bridge would have been simple for the first migrants.

5. people might have crossed a land bridge while hunting animals.