San Juan Cotzocon is a town and municipality in Oaxaca in south-western Mexico. It is part of the Sierra Mixe district within the Sierra Norte de …San Juan Cotzocon is a town and municipality in Oaxaca in south-western Mexico. It is part of the Sierra Mixe district within the Sierra Norte de Oaxaca Region. The name "Cotzocón" or "Cozogón" means "Dark Mountain".