To see how the world changes study economics.
Economics is a system of communication. It is no mistake that the first words you learn in a foreign language when traveling are those which enable you to buy things.
“How much does it cost?”
Trade is something that people everywhere can easily understand; it’s something that as a species we just get. One of my favorite types of stories are those of ancient mariners showing up on the shores of some remote locale for the first time and meetings with the people there. Almost invariably, if the two sides don’t immediately start killing each other, the rapidly engage in trade. Completely removed cultures all understood the same market fundamentals — which we really haven’t evolved very much away from today.
My first profession was in archaeology. I was young then and I gave it up as an academic pursuit when I realized that it was in large part the study of ancient economics. I wanted to believe that I would find these non-materialistic ancient cultures who understood the true essence of life that could be reinstated as a model for our time. (Like I said, I was young.) What I found instead were obsessive, and often violent, capitalists and empire builders.
You research migration via trade goods, you can watch how cultures changed over time by their commodities, the earliest forms of writing were accounting records. Trade shows cultural alliances, it showed who is up and who is down, who is driving innovation, and who is copying and trying to keep up. Every big social movement in history is shown in economics.
The central market is the most ethnically diverse place in any city.