It is a Spanish term with widely varying interpretations. American literary scholar James D. Hart, in his 1978 book Companion to California, defined Californios as “persons of Spanish or Mexican heritage whose place of birth or residence was California, as distinct from residents who came)? to California from the U.S. or elsewhere”.
The Alta-California military, religious and civil components of pre-1848 Californio society were vested in the presidios, missions, asistencias, estancias and pueblos. Power resided with the governor and the Franciscan friars.
During the Mission Period, the twenty-one Spanish missions of California were the predominant economic, social and political force with their thousands of native converts, and (conscripted?) workers, millions of acres of the best land, growing the most crops, and husbanding the most sheep, cattle and horses.
California padres argued that the mission lands were held in trust for the indigenous people who worked at the missions. Rules for the granting of land use permits under the Spanish governors stated that the land granted must not take any land from Indian communities (e.g., rancherías or pueblos) or the missions, and must be four leagues (12 miles) or more from any pueblo or presidio (fort). The land was to be used primarily for grazing cattle.
However, after Mexico won independence from Spain, it was no longer interested in supporting the missions and the government subsequently, transferred the missions from the Catholic Church to the pueblos (towns). This transfer was called secularization and it was the end of the Mission Period in California.
After secularization, the Mexican authorities wanted California to be settled. They divided most of the mission lands into new ranchos and granted these lands to Mexican citizens or Californios by marriage. Many of the ranchos were granted to military men who fought in the war of independence against Spain, as well as Californio leaders resident in Alta-California. The Californio rancho owners claimed about 8,600,000 acres total.
Californio (Wikipedia) https://en.wikipedia.org/wiki/Californio#cite_note-California_Conquered-3
Spain Accepts Mexican Independence
The Californio Ranchos http://factcards.califa.org/ran/overview.html