What is the setting in the novel, The Lord of Opium?

The main setting of Ajo, Opium is Matt's drug empire. It is comprised of a thin strip of land between the United States and Aztlan (the former Mexico), that is surrounded by other drug empires. Ajo is the city in which Matt was raised, the city where El Patron's hacienda is located. The hacienda is surrounded by opium fields and is Matt's main place of residence.