Tetradrachm

Kyrene's silver coinage was underpinned by one commodity more than any other: silphium, the now-extinct plant harvested from the Cyrenaican plateau that ancient physicians and cooks considered indispensable. The city held something close to a monopoly on it, and that economic leverage is precisely why a North African Greek colony could sustain such a confident, high-quality silver currency through the late fifth and early fourth centuries.

The silphium trade collapsed gradually — ancient sources including Pliny the Elder suggest it was already scarce by the first century AD, likely due to overgrazing. By then, Kyrene's monetary independence was long gone.