Sinope, Paphlagonia in Northern Anatolia is on the southern shores of the Black Sea and it is still a city today in modern Türkiye see map. This coin was issued in Sinope during the reign of Mithridates VI of Pontus, aka Mithriadates the Great, during the first century BC. Mithridates VI was born in Sinope around 135 BC to Mithridates V and Laodice VI. His father was poisoned in Sinope in 120 BC.
Attributing this AE20 coin isn't too challenging - ΣINΩΠHΣ, Zeus and an eagle make it pretty easy. "Recueil General Monnais Greques D'Asie Mineur" has a variant of this coin as "Sinope 59" with an AE monogram, without symbol, one of 4 variants listed. Coryssa has 2 (of 61 coins for "paphlagonia sinope eagle") and ACSearch has 1 (of 131 coins found with "sinope zeus eagle") with this particular monogram, no symbol combination. Other varieties are easier to find.
This coin appears to be from fairly fresh dies and very fine or better. More importantly, the coin fit my current interest in the coins and politics of the Roman republic during the time of Sulla, as a coin from the reign and birth place of Mithridates, who battled with Sulla in the Mithridatic Wars. Machiavelli describes Rome's encounters with Mithridates as "her empire in Asia was for a moment shaken" in his "Art of War". Paphlagonia was one of the territories that Mithridates agreed to relinquish in his treaty with Sulla (see Plutarch Life of Sulla 22).
Paphlagonia, Sinope, under Mithradates VI of Pontus, Circa 85-65 BC, Æ
Size: 18.5mm, 7.97g
Obv: Laureate head of Zeus right
Rev: ΣINΩΠHΣ, Eagle standing left, head right, on thunderbolt; AE monogram to left
Ref: Rec.Gen. 59 AE monogram w/o symbol
There is an interesting article in History Today on the changing representation by and perspective of historians on Mithradates VI over the years, by Andrienne Mayor author of the Poison King.