The settlement of Santa María de Bacerac was actually founded in the year 1645 by the Jesuit missionary Cristóbal García in Opata Indian territory.
Since 1493, the Kingdom of Spain had maintained a number of missions throughout Mexico, in order to spread the Christian doctrine among the local natives and facilitate Spanish colonisation.
These missions were particularly needed in Sonora, populated as it was by a number of disparate ethnicities which meant the Spanish could not simply co-opt one empire for domination purposes as they had done with the Aztecs in central Mexico. In addition, there was fierce Yaqui resistance to European intrusion on their lands.
Jesuit priests began to work in the Sonora area in the 1610s. They initially worked out a peaceful compromise with the 30,000 Yaquis allowing for the establishment of more than fifty mission settlements in the Sonora river valleys, before moving onto Opata, Pima and Tohono O’odham territories. Spanish exploration and missionary work was sufficient to consider the territory part of New Spain by 1637.