Sanatruces may have been a son of Mithradates I (reigned 171–138), the Parthian king who had established the kingdom's power. Following the death of King Mithradates II in 88 BC, dynastic struggles troubled Parthia, and the Armenians took advantage of the situation to invade the kingdom. Sanatruces sought refuge with the Sacaraucase, a Scythian tribe. Despite his 80 years, he was chosen as the prince best suited to deal with the dynastic question; he was made king of Parthia to clear up the succession and reunify the kingdom. On his death Sanatruces was succeeded by his son, Phraates III.