Rhea's myth is inseparable from the birth of Zeus, the stone given to Cronus in the child's place, the infant hidden in a Cretan cave, but her cult identity in the historical period was shaped above all by her identification with the Anatolian Cybele, the Great Mother (Meter). By the Classical period Greeks worshipped a Mother of the Gods whose ecstatic rites, drums and attendant Korybantes or Kouretes, the armed dancers who in the Cretan story drowned out the infant Zeus's cries, merged the two goddesses. In 204 BCE the Romans, on the instruction of the Sibylline books, imported Cybele's sacred stone from Asia Minor to Rome, where she became the Magna Mater served by the eunuch Galli, and Greek Rhea was folded into that great Mediterranean mother-cult. Her name in the older Italic layer is Ops, goddess of plenty.
Rome's adopted Magna Mater was honoured every spring with the Megalesia, a festival held in April that combined public games, including theatrical performances, with the goddess's own ecstatic rites; Roman drama's surviving record credits the Megalesia with hosting early performances of plays by Terence and Plautus, making the imported Phrygian mother-goddess, by extension, an unlikely patron of the development of Latin comic theatre. The self-castrating Galli priesthood that served her, drawn from outside the Roman citizen body since Roman law barred citizens from the practice, remained a visible and sometimes controversial feature of the cult throughout the imperial period, its foreign character never fully absorbed into ordinary Roman civic religion.