▁em peror ' s ▁appro val , ▁was ▁named ▁in ▁his ▁honor ▁as ▁Pet ra ▁Pia ▁Justin iana . ▁According ▁to ▁the ▁contemporary ▁historian ▁Pro cop ius , ▁Pet ra ▁was ▁founded ▁through ▁the ▁efforts ▁of ▁the ▁Roman ▁official ▁John ▁T z ibus , ▁who ▁there after ▁exerc ised ▁tight ▁control ▁of ▁imports ▁into ▁Laz ica ▁and ▁controlled ▁local ▁access ▁to ▁lux ury ▁comm od ities ▁and ▁much - ne eded ▁salt . ▁The ▁name ▁of ▁Pet ra , ▁literally , ▁" rock " ▁in ▁Greek , ▁was ▁a ▁reference ▁to ▁the ▁rock y ▁and ▁precip it ous ▁coast ▁where ▁the ▁city ▁was ▁built . ▁Its ▁location ▁between ▁the ▁sea ▁and ▁the ▁cl iffs ▁rendered ▁the ▁city ▁in access ible , ▁except ▁for ▁a ▁narrow ▁and ▁rock y ▁stretch ▁of ▁level ▁ground , ▁which ▁was ▁def ended ▁by ▁a ▁def ensive ▁wall ▁with ▁two ▁to wers . ▁ ▁Laz ic ▁War ▁ ▁T z ibus ' ▁mon opol ization ▁of ▁trade ▁in ▁Pet ra ▁sou red ▁Rome ' s ▁relations ▁with ▁the ▁L azi , ▁whose ▁king , ▁G ub az es , ▁secret ly ▁sought ▁S as an ian ▁assistance ▁against ▁Rome . ▁This ▁occasion ed ▁an ▁invasion ▁by ▁a ▁S as an ian ▁army ▁under ▁Kh os row ▁I ▁in ▁ 5 4 1 ▁and ▁twenty ▁years ▁of ▁war ▁in ▁Laz ica , ▁in ▁the ▁course ▁of ▁which ▁Pet ra ▁changed ▁hands ▁several ▁times . ▁In ▁ 5 4 1 , ▁Kh os row , ▁following ▁an ▁initial ▁un success ful