Narratives like The Life and Adventures of Joaquin Murieta, the Celebrated California Bandit provide us with a basis for understanding the ways that popular culture in its most general sense– as the culture of the popular classes, i.e., the people– dramatize and question socio-historical forces.
One of the roots of the land-grab that we’ve come to call the Mexican-American War concerns the spread of chattel slavery and the maintenance of the political and economic powers of the slaver class. The Republic of Texas was founded by slave-owners who wouldn’t abide by Mexican law, which in 1829 outlawed chattel slavery.
(Mexico also granted full rights of citizenship to free people of African descent, something the US would not do with full practical effect until the 1960s. Some slaves escaped and joined forces with Native American peoples such as the Cherokee, who had been ethnically cleansed from Georgia and the Carolinas. Recall that Yellow Bird identified as Cherokee.)
More to the point, perhaps, Pres. Polk, a slaveowner himself, fabricated a causus belli which congress and many US Americans were only too happy to swallow. The acquisition of these territories would led to a sclerotic disagreement between the north and south which ultimately erupted into a war that killed over 600,000 US Americans.
The US Mexican War:
These docs are available via the library (films on demand):
The Trail of Tears
The Gold Rush
To Conquer or Redeem: Manifest Destiny