Arcathias was a son of Mithridates VI of Pontus and his sister-wife Laodice.
[1] In 89 BC, Arcathias joined Neoptolemus and Archelaus, his father's generals, with 10,000 horses, which he brought from Armenia, at the commencement of the war with the Romans.
Two years afterwards, in 87 BC, he invaded Macedonia with a separate army alongside a general named Taxilas.
He then proceeded to march against Sulla, but died on the way, at Tidaeum (or Potidaea or Mount Tisaion).
[4][1] The commander of the army sent to Macedonia is called "Ariarathes" by Plutarch, but it's generally assumed that this is the same person.