[TeMPOraL]

That works within a community. What about inter-community trade?

[yxhuvud]

Then you can of course barter, but where do you think most human interactions happened during that time? Inside small groups of people that trust each other or between different groups that doesn't?

[TeMPOraL]

Obviously the former, but I imagine the groups quickly split as the population grew, and met further groups as they expanded.