The Challenge: Iranian/Persian symbolism help sought

I’m working on the Iranian chapter of The Banknote Book and have come across this interesting engraving on the front of Pick 30, the 1,000-rial note of 1934. The image—described in SCWPM as “warrior killing fabulous creature”—also appears on the date stamps of subsequent issues. I suspect it depicts some Persian legend or myth. If anyone can direct me towards a full explanation, hopefully identifying the warrior and/or creature by name, I would appreciate it. Thanks in advance!

IDENTIFIED: Darius the Great stabbing Ahriman monster from stone relief at Persepolis.

Courtesy of Raphael.