Flipping through David Graeber's Debt: The First 5000 Years

Turns out some of the first coinage was a means of providing field pay to soldiers. Its local circulation - combined with Roman taxation - was effectively used to extort occupied nations into paying for their own conquest. Locals were forced to pay the Roman designated governor in coin only Roman soldiers were provided, on pain of confiscation, enslavement, and death.

This practice of minting coinage to recollect as tribute has been a cornerstone of imperial economics into the modern day.