The discovery of silver in Cerro Rico, Bolivia, prompted the foundation of the mining town Potosí on 10 April 1545. Francisco de Toledo, the Spanish Viceroy of Peru from 1569 to 1581, created the so-called mita system. The Potosí mita was a state-coordinated form of draft labour whereby communities throughout the region were obliged to send a designated number of workers (men aged between 18 and 50) to work for specific mining concerns. The system was originally devised by the Incas, but the Spanish colonists adapted and expanded it to serve the needs of the mining economy.
Raquel Gil Montero considers the case of forced labour in Potosí and the large San Antonio del Nuevo Mundo mine in Southern Bolivia in an article in IRSH (56, 2011, special issue): 'Free and Unfree Labour in the Colonial Andes in the Sixteenth and Seventeenth Centuries'. The author focuses on the condition of indigenous workers as "free labourers", and the "mita" system of unfree labour.