The Tehuacán-Cuicatlán valley is a dry trench between the mountains of Puebla and Oaxaca, and it holds one of the richest deserts in the world. Rain falls rarely here, since the high ranges on either side block the moisture, and in that shadow grow forests of columnar cactus, some of the densest anywhere. Candelabra-shaped tetechos and tall organ pipes stand shoulder to shoulder across the hills, with agaves, yuccas and tree-like plants whose bark peels in red papery sheets.
UNESCO inscribed the valley in 2018 as a mixed site, for both its biodiversity and its place in the history of agriculture. People here began to cultivate maize, beans, squash and chilli thousands of years ago, and early farmers built canals and dams to water their fields. Near Purrón, a stone-and-earth dam from about 700 BC is regarded as one of the oldest in the Americas, and at San Juan Raya, fossil shells lie in the hills from a time when this was an ancient sea.
The roads through the valley are hot, curving and often empty. Highway 135 runs through a gorge, past salt works at Zapotitlán Salinas, where villagers have evaporated brine for centuries, and small towns where goat cheese and mole are sold. The landscape is very beautiful in the late afternoon, with the cactus casting long shadows, but the heat in summer can reach forty degrees, and storms in the rainy season cause flash floods in dry riverbeds. Winter is mild and the best season.
The nearest villages, such as San Juan de los Cués and Tecomavaca, are small, with limited services, and Teotitlán has more. Fuel can be sparse, so top up in Tehuacán or Oaxaca before entering. Carry plenty of water and a hat. Local cooks offer goat barbecue and tamales, and the cactus fruit, pitaya, is sold in season. Please do not collect plants or fossils, which are protected, and drive carefully for wandering goats.