Cuilapan de Guerrero is a town and municipality located in the central valley region of Oaxaca in southern Mexico. It is 10 kilometres to the south of the capital city of Oaxaca on the road leading to Villa de Zaachila, and is in the Centro District in the Valles Centrales region.
Cuilapan, originally called Sahayuca, has been a permanent settlement since at least 500 BCE. It developed into a city state but was absorbed by Monte Albán until between 600 and 900 CE. After this, Cuilapan returned to being an independent city-state, equal to a number of other important city states in the area. After the Spanish conquest, Cuilapan had a population of over 40,000 people with formidable social, economic and cultural institutions. For this reason, a major monastery dedicated to James the apostle was established there in the 1550s in order to evangelize the Mixtec and Zapotec populations. However, the area underwent decline of its native population in the 16th and early 17th century and the extravagant monastery complex would later deteriorate in the 19th century. Today, the town is a quiet place with a fraction of its former population and prestige.