It is found in the region Provence-Alpes-C Ã te d'Azur in the Bouches-du-Rh Ã ne department in the south of France .
Cassis ( ; Occitan : CassÃ s ) is a commune situated east of Marseille in the department of Bouches-du-Rh Ã ne in the Provence-Alpes-C Ã te d'Azur region in southern France .