Pilon

The Pilón valley lies east of the Sierra Madre Oriental, where the Pilón River crosses the foothills of northeastern Mexico. Its land and water attracted Spanish settlement in the seventeenth century, although Indigenous peoples already lived in the surrounding country. The valley linked mountain routes with the lowlands of the Nuevo Reino de León.

In 1637 the governor granted land in the valley to Alonso de León. A house and chapel were built at Pilón Viejo, and in 1665 his son established the hacienda of Nuestra Señora de Regla beside the river. The settlement that grew around it later became Montemorelos. A church dedicated to San Mateo preserves the older name of the valley. The hacienda became a focus for further settlement along the river.