Chiles are actually a fruit that belong to the genus Capsicum. Most of the chiles found in Mexico are of the Capsicum annuum species, save for the chile manzano (C. pubescens), and the chile habanero (C. chinense). Based on archeological remains, it is known chiles were being consumed over 7,000 years ago in Oaxaca's Guila Naquitz cave. For millennia, chiles have provided a valuable source of vitamin A and C in the daily Mexican diet. Upon arriving in the New World, the Spanish conquerors and priests observed the important role chiles played in pre-Colombian society--as a tribute, medicinal remedy, weapon and versatile condiment. Early explorers and ethnographers, like Alexander von Humbolt and Fray Bartolome de las Casas, noted and compared the use of chiles in Mexico to the use of salt in Europe (i.e., used to season everything).
When discussing chiles in Mexico, it is important to talk about terroir. Chiles are as much a part of their environment as they are of the cuisine. Whether dealing with a dry and arid climate or one that is hot and humid, all of these factors have an impact on the particular flavor profile of a chile. There are many microclimates throughout Mexico that produce unique and rare chiles. Oaxaca serves as an example, as it is home to more chile microclimates than anywhere else in the world. The chile chilhuacle, chile chilcostle and the chile pasilla OaxaqueÒo, for example, are not grown outside their native Oaxaca and are essential ingredients for some of the state's well-known moles. Other chiles, like the chile manzano, can be grown only at higher elevations--at least 5,500 feet above sea level.