A lot of worldbuilding happens behind the scenes. Imports and exports are very important and should not be overlooked. Trade is a pretty basic concept that will affect almost every city or town in your world. These things will help set up world politics, which will in some way affect your MC. Whether it is the ingredients he has to cook dinner or the clothes on her back, trade will be a big factor.
I started by listing materials, crops, and goods my MC’s homeland would have. Wen is known for their various silks, teas, and crops. They also mine for many precious stones and make beautiful furniture from stone. I listed their goods and services.
Conflict is natural when one group of people has what another group of people wants. This can lead to war. To prevent a world of raiders that are constantly at war with one another, you might include alliances.
I listed which countries would be trade partners. These countries are going to have some kind of alliance. If your MC lives in a small town, they will also have trading partners with other nearby towns or perhaps a bigger city. I then listed the supplies that other countries would bring to the table.
Some resources to consider are grains, meat, fish, different metals, oils, wines, salt, spices, sugar, different kinds of lumber, and stone materials. These things will have different values, depending upon their scarcity.
Trade partners should have an agreed upon form of payment, whether that’s a barter system or a type of currency.
Once I know what is being traded, I focus on how it is being transported. This is going to depend on the transportation systems that you have developed in your world. Carts, trains, and ships can transport goods. Check out my post on realistic travel times, https://myjourneyasafantasywriter.wordpress.com/2020/11/22/worldbuilding-realistic-travel-times/.
The next thing I consider is the cultural impact of trade. Peoples don’t trade without influencing the other. Diet, clothing, ideas, and buildings are often inspired by other cultures. In my world, foreign foods are delicacies. Only the merchant class can afford them. Mostly imported foods would cost more, so there might be differences between what your rich and poor people eat.
Trade can make certain people rich. What impact does that have on class in your world? In my world, there is a schism between the moniless and those with money. The moniless live by the old communal ways, and those with money have adopted a capitalistic mindset. This sets up conflict in my story between these two classes.
When I make a trade map, (I do everything by hand) I overlay tracing paper to my original map to keep everything to scale. From there, I mark all known settlements. I take my list of allies, and I mark them with stars, then I connect the stars through paths that would make sense with my topography. There will be certain hubs that all routes will lead to. I personally didn’t spend a lot of time on the land map. The sea and rivers were the main modes of transport. The alliances and goods were what I found most important. If this is important to you, I included a link to a blog that was very helpful in establishing my own.
Some blogs I found: