(247 BC–AD 224) Persian dynasty.
It was founded by Arsaces (r. с 250–211? BC) of the Parni tribe, which originally dwelt east of the Caspian Sea and entered Parthia after the death of Alexander the Great (323 BC), gradually extending control southward. Arsacid power reached its peak under Mithradates I (r. 171–138 BC). The government was influenced by that of the Seleucid dynasty and tolerated the formation of vassal kingdoms. The dynasty legitimized its rule over former Sāsānian dynasty .