Plata y Presidios

San Miguel (later 'de Allende') was founded because of the Chichimecas and the silver. Chichimeca was the name that the Spanish gave to the indigenous peoples from the north. While the southern tribes, like the Aztecs, were sedentary; the northerners had guerilla tactics that made their subjugation more difficult. When the Spanish attempted to haul their new-found treasure to their ships, the Chichimecas were so skilled with bows and arrows that they were able to practically nullify the horses, swords and guns of the Spanish. They were fearless and elusive in the terrain they knew so well. They liked to capture and cruelly torture, enslaving native women and children, martyring Spanish friars, and leaving ghost towns in their wake. They had a very large territory and little hierarchical social structure. The Spanish sent at least two special detachments to impose order. They were not successful. They attempted to transport their spoils in large wagon trains, but the Chichimecas were still irrepressible.
So the Spanish solution was to found a series of presidios (prisons) and defensive towns. San Miguel was the first founded. It had been a native settlement with a small group of Spaniards that had, in fact, been abandoned about four years earlier following a Chichimeca raid. It was a superb site strategically, and on December 15th, 1555 Viceroy Velasco (pictured here) issued orders that made it the first in a chain of settlements meant to keep the barbarian Chichimeca at bay. About 50 Spaniards were given lands and commissioned with establishing houses, orchards, farms and ranches. The nearby natives were not to be disturbed by the new settlement, but would contribute to it by adding to its size.

In the end there were more than 30 presidios and frontier towns that made a safe network for getting the silver from the mines to the ports.

The Forty-Niners of Sixteenth-Century Mexico Author(s): Philip Wayne Powell Source: The Pacific Historical Review, Vol. 19, No. 3 (Aug., 1950), pp. 235-249 Published by: University of California Press Stable URL: http://www.jstor.org/stable/3635589

Presidios and Towns on the Silver Frontier of New Spain, 1550-1580 Author(s): Philip Wayne Powell Source: The Hispanic American Historical Review, Vol. 24, No. 2 (May, 1944), pp. 179-200 Published by: Duke University Press Stable URL: http://www.jstor.org/stable/2507832