Wikipedia
A tianguis is an open-air market or bazaar that is traditionally held on certain market days in a town or city neighborhood in Mexico and Central America. This bazaar tradition has its roots well into the pre-Hispanic period and continues in many cases essentially unchanged into the present day. The word tianguis comes from Nahuatl, the language of the Aztec Empire. In rural areas, many traditional types of merchandise are still sold, such as agriculture supplies and products as well as modern, mass-produced goods. In the cities, mass-produced goods are mostly sold, but the organization of tianguis events is mostly the same. There are also specialty tianguis events for holidays such as Christmas as well as for particular types of items such as cars or art.