When exactly these tetradrachms were being minted is still a matter of debate, but experts like Ilya Prokopov argue based on recent hoard evidence that it began ca. 168 BC, with the conquest of Macedonia by Rome during the Third Macedonian War. There is little known what the end date for the minting of these Thasos tetradrachms are, the hoard evidence is fragmentary. However, what was found is that the Thasos tetradrachms varied greatly in style and using hoard evidence it was found that Thasos tetradrachms were minted by various authorities outside of Thasos on the mainland. Some were for example minted by Thracian tribes on the Thracian mainland to support their military activities against the Roman invaders. An example of these beautiful original Thasian tetradrachms (courtesy of Nomos AG): However, based on hoard evidence and stylistic derivations from the original Thasos tetradrachms, Roman moneyers may have taken over the minting of Thasos tetradrachms in Thasos ca. 148 BC after previously allowing the Thasians to mint their own coins as agreed in the initial administrative policies. In tightening the control of the Thasians, the Romans turned out slightly cruder coins than the originals while retaining the original design, not having the same pride in ownership as their predecessors and needing to produce large quantities of coinage quickly. It was therefore not really a coin in the name "of the Thasians" anymore. It is not that unusual for the Romans to strike coins that didn't clearly indicate its authority. When the Romans ruled over Syria in the beginning, they produced coins in the name of the Seleukid king Philip I Philadelphos, with different style as the original and with only a small monogram indicating the issuing authority. My new coin struck as a late imitative Roman tetradrachm: Islands off Thrace, Thasos. AR Tetradrachm. “Imitative series”, circa 90-75 B.C. Obverse: Wreathed head of young Dionysos right Reverse: ΘΑΣΙΩΝ ΗΡΑΚΛΕΟΥΣ ΣΩΤΗΡΟΣ. Herakles standing facing, head left, holding club, lion skin draped over left arm; monogram to inner left. Reference: Prokopov, Silberprägung, Group XII, 739 var.; Le Rider, Thasiennes 52; HGC 6, 359. 16.7g; 32mm Roman administrators in Macedonia may have also minted Thasos-type tetradrachms beginning ca. 120 BC, to support Rome's war effort, bribing Thracian rulers and paying Thracian mercenaries. Probably ca. 75 BC these Roman imitations stopped being minted with a possible scenario that Rome began actively replacing these with its own denarii. Thracian tribes still struck these Thasos tetradrachm however, but in much more distinctive style compared to the Romans, see an example here. In auctions all Thasian tetradrachms are often just labeled as an original Thasian tetradrachm, even when the Romans were the producing authority of these coins. Only when the style is so off they are sold as Celtic imitations. Since the original Thasian tetradrachms were only minted for ca. 20 years, and the Roman imitations for ca. 73 years, it is not surprising if many people here on the forum actually own the Roman imitation rather than the original. The style is sometimes difficult to separate, especially in the beginning of these new Roman series. For my coin the style difference is rather obvious. Please share your coins of Thasos (and it's imitations)!