While awaiting new information, you might be interested in some of the answers given the last couple of times this question was asked:

https://amp.reddit.com/r/AskHistorians/comments/2q37ff/are_there_any_records_of_asian_or_jewish_cowboys/

https://amp.reddit.com/r/AskHistorians/comments/2hi9nf/were_there_ever_any_asianasianamerican_cowboys/