Hellenistic period
In 255 B.C., Ariarathes III took the title of king and married Stratonice, a daughter of Antiochus II, remaining an ally of the Seleucid kingdom. Under Ariarathes IV, Cappadocia came into relations with Rome, first as a foe espousing the cause of Antiochus the Great, then as an ally against Perseus of Macedon and finally in a war against the Seleucids. Ariarathes V also waged war with Rome against Aristonicus, a claimant to the throne of Pergamon, and their forces were annihilated in 130 BCE. This defeat allowed Pontus to invade and conquer the kingdom.

Q: Cappadocia began it's realtionship with Rome under whom?
Ariarathes IV