It is bordered to the north by Abejorral, to the east by Sonsón, to the southeast by Salamina, to the south by Pacora, to the west by Caramanta and Valparaiso, and to the northwest by La Pintada.

The municipality of Aguadas, located in the northern part of the department, was founded in 1808 by José Narciso Estrada.

These Indians were baptized with the name of Armados (Spanish for armed) apparently based on the outfits they wore.

The subsequent depletion of the ore led to the abandonment of the region, and finally the authorities ordered the transfer of Arma to the town of Rionegro.

One of the places of arrival for immigrants moving south from Antioquia was said to be the inn run by Manuela Ocampo, where the muleteers were given lodging.