How does trade work?

[Boogie Knight]

Without merchants, I'm struggling to understand how trade works. In vanilla M2TW, I know that securing trade rights with another faction allows your merchants to make extra money from resources within that faction's territory; but without merchants, what does it do in this? Bear in mind that aside from what I've just said, I don't really know what trade rights mean in the vanilla game either, but I'm specifically looking for how it works in Third Age.

[Flinn]

basically, trade happens between your own regions and between your regions and those of other factions you share the trade rights with.

if you go into the settlement page and click to show details (it opens another page on the left side), you can see two small buttons below: one is for changing capital, the other will show you the trade and economic summary of your region.
Looking closely at it will allow you to see which resource is sent or imported to and from your specific region (similar recources will not be swapped, i.e. you can't trade gold with a region that already has gold as a resource).
The trade will generate income automatically, and is increased by: better markets, better roads, governor abilities and anchillaries

In my experience, trade rights are really important especially when you have ports in regions that are valuable for trade, because with the trade rights you can open up variuos possible routes for your products that will be exported at any distance to a port (or more than one, depending on the level of merchant warf you have) controlled by a faction you have trade rights with
there is more to say of course, feel free to ask specific questions if you are in need

edit:

below is a picture about settlments details (taken from Incomitatus' guide a lecture I suggest to all the newbies of TATW)

Spoiler Alert, click show to read: 

[Greymane]

Without merchants, I'm struggling to understand how trade works. In vanilla M2TW, I know that securing trade rights with another faction allows your merchants to make extra money from resources within that faction's territory; but without merchants, what does it do in this? Bear in mind that aside from what I've just said, I don't really know what trade rights mean in the vanilla game either, but I'm specifically looking for how it works in Third Age.

Trade in TATW works exactly the same as in vanilla.
Few thing to keep in mind:
- Resources are important. Provinces with gold or ivory will make huge amounts of money by trading alone.
- The more regions a region borders, the more regions it can trade with. Sea trade works slightly differently, in that the ports are connected, not the regions. Ports can be pretty far away (follow the green lines).
- In both cases: trade happens between regions owned by the player and regions that the player has trade rights with. Neutral regions (no trade rights) contribute something to trade income, but not as much. Trade with hostile regions is out of the question.
- There are a lot of buildings that affect trade. It is highly recommended to build them.
- As a rule 1st and 2nd tier roads, 1st tier ports and naval trade buildings affect trade the most. Roads are especially important for trade and they allow your troops to move faster, making building them a no-brainer. Markets add a little income for a relatively small amount of money, so they are useful too.
- Check the settlement overview to see how much a province is making in trade and how much the buildings mentioned above affect trade.

Edit: Ninja'd

[DrDragun]

Trade is only calculated as 'trade income' for each settlement, there are no merchants as you know. Securing Trade Rights usually adds significant income to your nation. There is evidence that distance is a part of the equation (central settlements make more income from trade). Also, markets, roads, and ports increase trade income.

It's interesting to try to figure out the detailed mechanics of trade, but in TATW this information won't really help you make any gameplay decisions because the decision is already easy: get trade rights with all other good or evil factions.

[Boogie Knight]

You guys rock! Thanks for the info!

So is the settlement info screen the best way to measure the benefits and progress of trade? I suppose what I'm looking for is a way to measure how well I'm doing with it. From what you're all saying it sounds like the only way for it to go, really, is up. So I secure trade rights, build roads, ports, markets etc. (in that order?) and watch the results come in, and then I shouldn't really have to do anything to "maintain" it, right? Is there any worth to prioritising conquering regions with useful and unique trade resources? I guess that like everything else that'd depend on the situation.

[Greymane]

You guys rock! Thanks for the info!

So is the settlement info screen the best way to measure the benefits and progress of trade? I suppose what I'm looking for is a way to measure how well I'm doing with it. From what you're all saying it sounds like the only way for it to go, really, is up. So I secure trade rights, build roads, ports, markets etc. (in that order?) and watch the results come in, and then I shouldn't really have to do anything to "maintain" it, right? Is there any worth to prioritising conquering regions with useful and unique trade resources? I guess that like everything else that'd depend on the situation.

Yes, and you can look at the financial overview to see the total trade income from all settlements.
There is also a button on the left bottom of the settlement details (the one with the scales) that will give you an overview of what goods go to what region. It's not entirely accurate in TATW, as the trade income is only 90% (don't quote me on this, but something like that) of what it is in MedII. So: 50 worth of common goods going from Minas Tirith to West Osgilliath will show up as 45 in the settlement details and will only get you 45 income. It will give you a very good indication of what makes the money for you, though, and will help you find out what resources and regions are the most useful.
I don't think it's really worth it to prioritize conquering settlements specifically for their trade, but if you can take a region with valuable resources that is not a strategic nightmare, go for it

[Flinn]

So is the settlement info screen the best way to measure the benefits and progress of trade?

actually yes, it gives the most detailed info; you can also check the overall economy summary to see how you are doing with trade faction-wide

So I secure trade rights, build roads, ports, markets etc. (in that order?) and watch the results come in, and then I shouldn't really have to do anything to "maintain" it, right?

yes, you don't need to do anything in particular to maintain this, apart from repairing building that might be damaged by enemy armies or agents. In my opinion always build roads first, then markets, then ports (and merchant warfs).
If you have a special love for trading income, have a look at the guide I linked you before, in particular in the section on how to train governors with good trading skills; be aware anyway, the first source of income in TATW will always be taxation (the ratio is about 2/4 from taxes, 1/4 from trade and 1/4 from farming, approximately). It is worth to train a governor with high trade, taxation and farmig skills (all together) only for the best settlements you have in terms of money-making.

when you evaluate how worth is a region for trade, also consider:

the best trade resources are those linked to mines, because you can both mine and trade them (gold is the best ever).
an inland region can only trade with it's neighbours, therefore if you have 10 resources in that region but it borders only 2 regions, it will probably give you less income than a smaller area with 2/4 resources, but that borders 6/8 regions.
a sea region can trade via ports for a number of fleets established depending on the level of the merchant warf, therefore sea trade needs an higher investment than land trade to have it grow consistently

You guys rock! Thanks for the info!

our pleasure

[DrDragun]

Re: maintaining trade. Well obviously, if you are Gondor make sure you kill any boats blockading your ports Other than that, you can try to develop trading traits in a governor, but governor-training is a more advanced facet of gameplay that can take a lot of specific knowledge and not add much value for the amount of effort. One thing to note: if you have a governor in a settlement with no Grain Exchange (the lowest market) he has a VERY high chance of getting the "Bad Trader" trait each turn, (reduces trade income by 10/20/30%) so that's definitely one to avoid. Also, it's not specific to trade, but settlements that are distant from your capital have more corruption, reducing all forms of income, which you can improve by increase the Law in the settlement (barracks, council chambers, governor traits).

[Withwnar]

Re: maintaining trade ... kill any boats blockading your ports

... and enemies standing on your roads. e.g. Rebels have a habit of standing for prolonged periods in one spot; if it's on a road that is a trade route with a neighbour then that trade is reduced.

EDIT: also, enemies standing on your port blockades it, just like ships.