… is from page 10 my GMU Econ colleague Larry White’s 2023 book, Better Money: Gold, Fiat, or Bitcoin? (original emphasis; reference deleted; link added):
The claim that state power is or sovereignty is an essential or primary condition for any currency to become a commonly accepted medium of exchange is, however, plainly at odds with the historical fact that privately issued banknotes without sovereign guarantees were the dominant media of exchange in the eighteenth and nineteenth centuries where they were allowed. It is also inconsistent with the fact that privately minted silver and gold coins were widely accepted when and where they were allowed (which was rarer), as in gold-rush California and apparently in ancient Lydia where some of the earliest coins were struck.