On of the most interesting ideas I've read on this is from Debt The First 5000 Years, written by an anthropologist who took the approach of studying how societies actually use money rather than the economists approach of coming up with theories without much looking at real people.

Basically he says the idea that it originated from barter is pretty much never found in the historical record. 'Primitive' societies tend more to tally favours so you give someone food one day, it's remembered and they help you fix your roof another, without any formal currency measure. Formal currencies were often forced on people with threats of violence to get the natives to do stuff. Say you want to raise an army you declare a tax on everyone of so many coins which they can earn by feeding or serving in your army and people who don't come up with the tax are attacked in some manner.

Or you come up with some debt everyone owes and that kind of thing. Eg from the book

>In 1895, for example, France invaded Madagascar...

>...and declared the country a French colony. One of the first things General Gallieni did after “pacification,” as they liked to call it then, was to impose heavy taxes on the Malagasy population, in part so they could reimburse the costs of having been invaded...

leading on to in the modern day:

>But owing to IMF-imposed austerity programs, the government had to cut the [malaria] monitoring program. Ten thousand people died. I met young mothers grieving for lost children...