You are correct: based on the Elymaeans that have hit the market in recent months, particularly through Lanz, it's clear that a very large hoard was recently discovered. It seems to be endless, consisting of mostly AE drachms, but also some tets, all from the Elymais Arsacid Dynasty, when the rulers were likely blood kin to the Arsacids of Parthia. New lots are still appearing weekly. I think I vaguely recall reading about a hoard find (of Elymaeans) a year or so back, but I don't remember the specifics...surely these coins are from that find.
Most coins from the hoard are in rough shape, with wear, corrosion, and deposits. But here and there are some very nice specimens. I snagged one last month, an Orodes IV drachm similar to yours - but, alas, your Artemis has held up much better through the centuries than mine has.