Every once in a while they might come together with other bands, possibly in seasonal festivals at which they would share news and knowledge as well as giving young people the opportunity to find a mate outside their tiny community.
This relays to some of the reasons why new inventions and news about what people were learning spread. People were able to meet up with each other and share what new tools or inventions they had made. They might have even had the chance to share new foods as well. This can somewhat explain to how different regions of the world started farming.