BACIΛEΩC PHCKOΠOP, bust of King Rhescuporis wearing ribbon right, trident in front of the face, beaded circle / Laureate and draped bust of the Roman Emperor Constantine the Great right, BP-X in fields (for 622 BE = 325/326 AD), all within a beaded circle. 20mm, 7.62 grams. Mint of Pantikapaion. Anokhin 771 var (this type is the one with the trident).
This actual coin is shown on the bosporan-kingdom catalogue website.
The Bosporan Kingdom, also known as the Kingdom of the Cimmerian Bosporus, was an ancient state located in eastern Sarmatia and the Taman Peninsula, on the shores of the Cimmerian Bosporus (now known as the Strait of Kerch). It was named after the Bosphorus, also known as Istanbul Strait, a different strait that divides Asia from Europe. The Bosporan Kingdom was the longest surviving Roman client kingdom - it probably lasted until the later 4th century, when the kingdom was probably finally overrun by the Huns, who defeated the nearby Alans in 375/376 and moved rapidly westwards towards the Roman empire.
The client Kings of Bosporus minted a fascinating series of coins dated in the local era. The gold/silver/billon and copper staters showed the bust of the Roman Emperor on one side and the bust of the King of Bosporus on the other side.