How is communism like how people lived 10,000+ years ago? Communism is how all people lived 10,000+ years ago.
Food.
> how exactly would one band of hunter gatherers continually oppress another band of hunter gatherers over a period of time?
They wouldn't, they'd just kill them before the need arises. But if they really wanted to, out of greed or laziness, they'd do what humans have done for thousands of years. Establish a hierarchy based on power and violence, and extort taxes.
Once there is a hierarchy with taxes and such you no longer have a migratory hunter-gatherer band. So you're talking about what happened during the agricultural revolution 10,000 years ago. I am talking about what happened before that.
Besides that, I don't think it's absolutely necessary for a hunter gatherer band to be migrationary, that's only when a tribe becomes too big and exploits its territory faster than the territory can recover.