Actually, the story began before the Gold Rush. Of the 44 founders of El Pueblo de Nuestra Señora la Reina de los Ángeles del Río Porciúncula (Los Angeles), 26 were considered "Negro." See John M. Weatherwax, The Founders of Los Angeles (Bryant Foundation 1954). Many of the prominent families of the early Californios, such as the Picos, would be considered "Black" today. See Damany M. Fisher, Discovering Early California Afro-Latino Presence (Heyday 2010).

And then there is fictional the Black Amazon Queen who gave California its name - Queen Calafia. (from the Sergas de Esplandian).