Anza is refering to the native peoples living in the area.

"Heathen" is a poor translation of the Spanish word "gentil" which gives a negative connotation of the reference Anza was making to the indigenous, or native peoples. "Gentil" means gentile in the English language, or a person who is not of the same religion as the speaker. Thus, Anza was referring to these people as "non-Christian" or "non-Catholic." (D. G.)