The opening credits show Joshua Trees in silhouette. They are native to the Mojave Desert, a popular California location for early film crews. And they are not real trees, but a relative of the lilly family.
This film was so successful it prompted the production of three more all-black westerns starring Herb Jeffries that were released from 1938 to 1939. However, for the following films his character's name had to be changed to "Bob Blake" for copyright reasons.
An article from 1940 in the New York Age, a prominent African-American newspaper, noted this film was the most profitable film with an all-black cast up to that time.
The star of this picture, the brawny 6'7" African-American cowboy actor, Herb Jeffries, made his living as a jazz baritone with the Duke Ellington Orchestra. He acted on the side.
Herb Jeffries had a light complexion. He had to wear dark makeup to cover it.