On the left (on your side), the interface shows you how much you earn with the trade and resources you export to your trading partner. The right side shows how much money they earn and what resources you import from them. I have never seen evidence that more commercial resources would increase the likelihood of someone agreeing to a trade agreement. The diplomatic system is very veiled here. I have seen that groups with 200-plus relationships are opposed to profitable trade for them and that groups with 5-strong relationships accept the same trade. Animal men, greenskin and chaos warriors cannot act. Trade can take place between two political groups in campaign mode. Trade agreements can be concluded on the diplomatic screen, allowing political groups to exchange trade resources and generate additional revenue for both factions. The Empire`s income comes from a variety of sources. The most important taxes are applied to the entire population and just behind them you have the trade. The income from slavery depends heavily on the amount of slaves you have enslaved during your conquests (it is a simple multiplier of basic income in the provinces). In addition, you can get an annual tribute to the conquered nations and rewards for the conclusion of the mission that was ordered by the Senate.
The next tab shows the details of the trade. If you have a trade agreement with another country, you can see here a list of resources imported and exported with their prices. Imports of construction resources are very important in the later stages of the game, when the larger structures available do not need easily accessible resources such as marble for example. Note: The Tomb Kings are the only faction that actually uses resources for their mortuary cult mechanics (Edit: a similar mechanic called forgery has been added to the dwarves in Warhammer 2 only since this response was originally published). For all other groups, resources only increase the value of trade agreements. So you`re generally right to think that these resources are not actually used by the trading partner, but not in this particular example. Trade can only be concluded between two groups if their capitals are connected by roads or waterways, and usually only if relations are good. Roads on land cannot cross the territory of another group.
First of all, it`s not true, because the Tomb Kings won`t use a lot of my resources, so they don`t matter. More importantly, it indicates that the other party is benefiting from the fact that I have more resources. The only interactive part of this window is the ability to set the level of taxation. This bar should only be used to reduce all rebellious moods throughout the empire by temporarily cutting taxes or to accelerate the development of different regions. If you make vast conquests, is much more convenient to put taxes in the newly conquered province to 0 than to change the level of taxation for the entire empire. Imagine this: „I make so much money to export this and this.“ This window is available under 7 keys. In the first Tax tab, you can set the level of taxation for the entire empire. Higher tax levels quickly fill your public purse, but also increase people`s discontent. Extreme levels of taxation can also stop the influx of people and thus the expansion of your provinces. It seems strange to me, I should be the beneficiary who has more means.
The more resources you have, the more likely it is that this group will sign the treaty. In your example, you will receive 620 golds per train and no resources, while Arkhan will receive 110 gold and all these resources on your side. Regular expenses include salaries, fleet maintenance and the potential tribute you must pay to your more powerful neighbor. The last tab summarizes the finances of the last two rounds. The information available here is much more detailed than in the Tax tab. You can easily see here where you are losing money and counteract these trends.