According to a very confused story by Diodorus of Sicily,note[Diodorus, Library of World History 31.19.] Orophernes was the brother of Ariarathes I, and fought for the Achaemenid king Artaxerxes III Ochus when his commanders Bagoas and Mentor of Rhodes reconquered Egypt (343 BCE). When he died, Orophernes left behind two sons, Ariarathes II and Aryses.
During the war between the Macedonians and Persians, Ariarathes I had gained some independence in Cappadocia, but after the death of Alexander the Great in 323, his successor Perdiccas defeated the Cappadocian and killed him. In the confused years that followed, Antigonus the One-Eyed controled Anatolia, but when he fell duing the battle of Ipsus (301), Ariarathes II seized control of the realm that had belonged to his uncle, and was recognized as a semi-dependent ruler by king Seleucus I Nicator.