[bluGill]

Barter is so bad for complex transactions that it couldn't go that way. Every transaction that needs to based on more than trust that you will get your gift back later needs some universal coinage. A trader can only take grain in your village, then in the city only pay in grain, but anything more complex needs money.

[snapcaster]

Yes this is what economists say, the truth of development is a lot more complicated. Suffice to say you're massively underestimating how complex debt/non-coinage based economies can be