When you create a timeline, you focus most of all on the major events that took place over a period of time. Although these events did not take place in isolation, they are presented as separate events, with the period in-between being unaccounted for. On the other hand, when constructing a historical narrative, you also build on the story that connects these events. Therefore, a historical narrative would discuss these topics in more detail.
Trade was a commonly used way to obtain items back in the day, people would give one item in exchange for another, allowing people to have access to items they didn't have before.
In its simplest form the domain is all the values that go into a function, and the range is all the values that come out. But in fact they are very important in defining a function.
