▁name ▁adopted ▁by ▁all ▁Par th ian ▁k ings . ▁The ▁Ar s ac id ▁dynast s ▁laid ▁claim ▁to ▁descent ▁from ▁Ar tax er xes ▁II . ▁Begin ning ▁from ▁Ast ab ene ▁and ▁Par th ia ▁( which ▁would ▁subsequently ▁be ▁extended ▁south wards ▁to ▁include ▁much ▁of ▁present - day ▁S istan ), ▁the ▁Ar s ac ids ▁gradually ▁sub j ug ated ▁many ▁of ▁the ▁neighbor ing ▁kingdom s , ▁most ▁of ▁which ▁were ▁there after ▁controlled ▁as ▁v ass al ries . ▁Begin ning ▁with ▁the ▁successful ▁revol t ▁- ▁in ▁ 2 2 4 ▁CE ▁- ▁of ▁an ▁erst while ▁v ass al ▁of ▁St ak hr ▁named ▁Ar dash ir ▁( in ▁Greek ▁again ▁" Ar s aces " /" Ar tax er xes "), ▁the ▁Ar s ac id / Par th ian ▁h eg em ony ▁began ▁to ▁yield ▁to ▁a ▁S ass an id / Pers ian ▁one . ▁ ▁The ▁name ▁" Par ni " ▁re app ears ▁in ▁S ass an id - era ▁documents ▁to ▁identify ▁one ▁of ▁the ▁seven ▁Par th ian ▁fe ud al ▁families ▁al lied ▁with ▁the ▁S ass an id ▁court . ▁However , ▁this ▁family ▁is ▁not ▁att ested ▁from ▁Ar s ac id ▁times , ▁and ▁the ▁claim ▁to ▁the ▁" Par ni " ▁name ▁is ▁( like ▁four ▁of ▁the ▁six ▁other ▁families ) ▁" in ▁all ▁probability ▁not ▁in ▁accord ance ▁with ▁reality ." ▁" It ▁may ▁be ▁that ▁[...] ▁members