According to some sources Darius appointed his closest friend Hydarnes as satrap of Armenia after the unsuccessful rebellion of Armenia and Media against Persians (around 522BC).

 According to some sources Darius appointed his closest friend Hydarnes as satrap of Armenia after the unsuccessful rebellion of Armenia and Media against Persians (around 522BC). The Persian pronunciation of this name is Vidrna.

Some scholars proposed that Erwanduni (Orontid) dynasty was descending from Hydarnes grandson. Others proposed that Hydarnes and already present Erwanduni became relatives via intermarriages. Apparently at last three different Hydarnes ruled Armenia before the Orontes mentioned in Xenophon.

Anyway all this are just hypothesis. But an interesting thing is that this name can have an old presence in Armenia.

Aram Kosyan discuss the ethnic structure of Ishuwa and mentions a name Uitarna- for which he gives a possible Indo-Iranian origin. The name is attested in Late Bronze Age.

In Urartian texts a land and a population group Uiteruhi is mentioned somewhere in upper Arax. So another possibility is that the Ishuwan Uitarna- simply descend from this nearby tribe and not from Indo-Iranians.

And another possibility is that Uiteruhi tribe itself is of Indo-Iranian stock and subsequently the Uitarna- name also.

This raises the possibility that the three successive rulers named Hydarnes in Satrapic Armenia are from local stock and not appointed by Darius.

Offcourse without any new ancient record this question will remain unsolved. To further complicate the matter the Uiteruhi is suspiciously close to Armenian term *wetar ( modern Getar , term attested in Ptolemy) . So it's possible that some of this similar looking terms have different etiology.

https://en.m.wikipedia.org/wiki/Hydarnes