La Roche-sur-Yon is a commune in the Vendée department in the Pays de la Loire region in western France. It is the capital of the department. …La Roche-sur-Yon is a commune in the Vendée department in the Pays de la Loire region in western France. It is the capital of the department. The demonym for its inhabitants is Yonnais. Known for its historical significance and cultural heritage, La Roche-sur-Yon also houses a wide range of educational institutions, from primary schools to higher education establishments.