Rancho San Bernabe was a 13,297-acre (53.81 km2) Mexican land grant in the Salinas Valley, in present-day Monterey County, California.
In 1842 Ríos bought the Molina land grant and moved his family to Rancho San Bernabe.
The Ríos family began raising cattle and crops on this land and producing wine from their own grapes.
In 1845 Petronilo Ríos bought Rancho Paso de Robles near Mission San Miguel and moved there with his family.
With the cession of California to the United States following the Mexican-American War, the 1848 Treaty of Guadalupe Hidalgo provided that the land grants would be honored.