Olmec colossal heads by Matthew Stirling in 1938 spurred the first archaeological investigations of Olmec culture. Seventeen confirmed examples are known from four sites within the Olmec heartland on the Gulf Coast of Mexico. Most colossal heads were sculpted from spherical boulders but two from San Lorenzo Tenochtitlán were re-carved from massive stone thrones. An additional monument, at Takalik Abaj in Guatemala, is a throne that may have been carved from a colossal head. This is the only known example from outside the Olmec heartland. Dating the monuments remains difficult because of the movement of many from their original contexts prior to archaeological
History of the world pre-Columbian societies were built, the most notable being the Zapotec Empire (700 BCE – 1521 CE), and the Maya civilization, which reached its highest state of development during the Mesoamerican Classic period (c. 250–900 CE), but continued throughout the Post-Classic period until the arrival of the Spanish in the 16th century CE. Maya civilization arose as the Olmec mother culture gradually declined. The great Mayan city-states slowly rose in number and prominence, and Maya culture spread throughout the Yucatán and surrounding areas. The later empire of the Aztecs was built on neighbouring cultures and was influenced by conquered peoples such