Located in the basin of the river of the same name —whose Nahuatl meaning is “river of the butterflies”— it is one of the most fertile areas of Veracruz. It includes municipalities such as Tlacotalpan, Cosamaloapan, Alvarado, Carlos A. Carrillo, and Tres Valles.

Characterised by its deep indigenous, African, and Spanish mestizaje, this region is recognised as the main stronghold of son jarocho, a traditional Veracruz musical genre. Dances such as fandango jarocho, La Bamba, and danza de la iguana are part of the cultural heritage, accompanied by jarana, requinto, and arpa jarocha. Events like Festival del Son Jarocho and Fiestas Patronales de Cosamaloapan celebrate this artistic and spiritual richness.

The gastronomy stands out for its use of local ingredients, especially from the river. Typical dishes include caldo de pescado blanco del Papaloapan, arroz a la tumbada, tamales de cazuela, chileatole, mole de olla, and a variety of traditional sweets such as cocada and jamoncillo de leche.