It extended easterly from San Antonio Creek to what is now Hermosa Avenue, and from today's Eighth Street to the mountains.

In 1839, the rancho was granted by the Mexican governor of California to Tiburcio Tapia, a wealthy Los Angeles merchant.

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.

Maria was thus a wealthy heiress, and Rains invested in three ranchos and the Bella Union Hotel in Los Angeles.

[8] Ramon Carrillo always maintained his innocence of the crime, but he was shot in the back from ambush and killed on the Los Angeles road west of Cucamonga on May 21, 1864, in another unsolved murder.

Isaias W. Hellman, a Los Angeles banker, and a San Francisco business syndicate acquired the 13,045 acres (52.79 km2) Rancho Cucamonga at a sheriff's sale in 1871.