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
Mayan languages from that branch at a much later date than proposed by Kaufman. In the Archaic period (before 2000 BCE), a number of loanwords from Mixe–Zoquean languages seem to have entered the proto-Mayan language. This has led to hypotheses that the early Maya were dominated by speakers of Mixe–Zoquean languages, possibly the Olmec. In the case of the Xincan and Lencan languages, on the other hand, Mayan languages are more often the source than the receiver of loanwords. Mayan language specialists such as Campbell believe this suggests a period of intense contact between Maya and the Lencan and Xinca people, possibly