K behind the head on reverse as date RY20 = (AD57/58)
Caius Julius Polemon II of Pontus (born in 10-15, died after 64) was a Roman client king appointed as king of Pontus, Bosporus, and Colchis in 38 by Caligula. His reign over Bosporus and Colchis ended around 39-41, while he continued to rule Pontus until 64. (source Wikipedia)
