- Mar 2012
Scribe my friend:The Xiongnu were definitely more formidable than Parthia, as Xiongnu expansionism caused a westward migration domino effect of Yuezhi fleeing west to escape the Xiongnu, which caused the Yuezhi to displace the Saka who had to flee further west to escape the Yuezhi migration. This caused much trouble for Parthia (the Yuezhi took a chunk of Parthia territory and the Saka killed two Parthian Kings). The later Huns of Eastern Europe however were beaten back by the Sassanids who were the successors of Parthia, albeit to be fair the Sassanids were also stronger than Parthia.
Parthia had trouble with the Scythians because they had an army annihilated when Greeks allies walked off the field. Those resources were hard to replace, and, as you said, they lost a second battle. Mithradates II reversed this trend by defeating the Saka. Of course, they later incorporated Saka into the army.
So it is a little more complex than A beat B beat C beat D.