The Tehuacán-Cuicatlán biosphere reserve is a protected natural area located in southeastern Mexico.

Its name derives from its two main locations: Cuicatlán and Tehuacán, in the latter are their administrative offices, covers 490,186 hectares distributed among 21 municipalities in the state of Puebla and Oaxaca.

The Santo Domingo flows eastward through the Sierra Madre de Oaxaca to join the Papaloapan, one of the largest rivers of Mexico.

The Salado and Grande rivers receive waters of numerous streams that originate in the neighboring sierras.

Contrary to popular belief, dry tropical regions that abound in southeastern Mexico are not poor in biodiversity.

Some studies, such as those by Rzedowski in 1973 and 1978, have led to the conceptualization of the area as a Floristic Province, belonging to the Mexican xerophytic Phytogeographical Region.