Also barter was never really a thing: However, ethnographic studies have shown that no present or past society has used barter without any other medium of exchange or measurement, nor have anthropologists found evidence that money emerged from barter, instead finding that gift-giving (credit extended on a personal basis with an inter-personal balance maintained over the long term) was the most usual means of exchange of goods and services
If you look at a pidgin English dialect like Nigerian pidgin, and compare it to British English or for that matter Nigerian non-pidgin English, you might assume that pidgin English was the original form, since it's simpler, and that British English evolved from it. But in fact the truth is the opposite: pidgin English is a simplified version of English developed as a lingua franca for international communication.
The same seems to be true of hard currency and especially barter. Hard currency is pidgin banking; barter is pidgin hard currency. Rai stones show us the complexity of social arrangements surrounding money that in a homogeneous culture within a generation or two, but which are only legible to someone who grew up in the culture to which that money belongs. In Yap this heritage has been preserved, although diminished in importance; elsewhere it has been mostly lost.
Hard currency is sufficiently simple to bridge cultural gaps and even gaps between ages, like pidgin English or Glosa.
One of the most interesting things I've heard about money is what Giordano Bruno (1548 – 1600) supposedly said: "Whatever has the greatest value and the least cost of storage becomes money."
Tribes traded people for goods and services, sometimes temporarily. It was mostly a sex and politics thing, but the book views it as a form of currency bartering and trade; I think there is more nuance there.
It reminds me of the aliens in Douglas Adams' who, having fifty arms, are the only species to invent under-arm deodorant before the wheel.