 Tlatilco culture shows a marked increase in specialization over earlier cultures, including more complex settlement patterns, specialized occupations, and stratified social structures.In particular, the development of the chiefdom centers at Tlatilco and Tlapacoya is a defining characteristic of Tlatilco culture.This period also saw a significant increase in long distance trade, particularly in iron ore, obsidian, and greenstone, trade which likely facilitated the Olmec influence seen within the culture, and may explain the discovery of Tlatilco-style pottery near Cuautla, Morelos, to the south.