Antiochis was a daughter of the Seleucid king Antiochus III the Great and his wife Laodice. Some time before the war of her father against the Romans she married king Ariarathes IV of Cappadocia,[2] who therefore supported his father-in-law in the battle of Magnesia (190 BC).[3] However, Antiochus III lost the battle. Antiochis bore her husband a son, who was called Mithridates before his accession to the throne and succeeded his father as Ariarathes V of Cappadocia, and two daughters, among them Stratonice, who first married king Eumenes II of Pergamon and afterwards his brother and successor Attalus II Philadelphus.