Hunter-Gatherer groups rarely traded with each other because they mostly focused on the resources they had nearby.
What was trade like in the Paleolithic Age?
Can you give me an important change?
Sure. The first important change is the spread of knowledge. With traders travelling far and wide, they encountered new people and obtained new knowledge which they spread elsewhere.
The last important change is resources. Traders set out to find and trade resources. Trading resources was important because it dispersed new and old resources which allowed people to get resources that they would have otherwise not have gotten without trading.
Because if people hadn't ever started to trade, many of the things we take for granted, would not be in our processions. Also, humanity without the knowledge that we got through trading, would have grown very separated.