Trade goods come in a wide variety of types, with 34 different trade goods divided into 6 categories. They allow you to tailor your provinces, and even more so your country, to your needs and desires by controlling what you produce and where you ship it, and are particularly important.
Every territory produces one type of trade good, and all territories in a province contribute their trade goods into a common pool. A territory produces 1 trade good by default (with 2 for cities and 3 for a metropolis), but can produce more with enough slave labor. For each additional 15 slaves in a settlement and 20 slaves in a city or metropolis (rounded down), the territory will produce one more additional trade good.
The threshold for a surplus is reduced for each territory by the Slaves needed for Local Surplus modifier, and across all territories in the country by the Slaves needed for Surplus modifier. Sources of these modifiers include:
- -2 by the "Land Seizure Protocol" Land Reforms Law (Requires Civic Advances level 12)
- -1 by the level 7 Slave Latifundia Civic Invention
- -2 by farmland terrain type
- -5 by a farming settlement or a mine
Some territories also have unique permanent modifiers giving surplus threshold reductions, such as the Rhodian Glass Workshops in Rhodes or the Cedars of the Gods in Phoenicia.
Additionally, the Base Resource Production modifier increases the base number of trade goods produced regardless of the number of slaves in the territory. The most important sources of base resource production are cities and metropolises, which give +1 and +2 base resource production, respectively. This means that cities are still a significant source of trade good surpluses even without the high slave ratios and slaves needed for local surplus modifiers that settlements and their buildings give.
Surpluses and trade
- Main article: Trade
A province will have a trade good surplus if it produces more than one of a certain trade good, either because it has more than one territory producing the same trade good and/or if its territories have enough slaves to produce multiple resources in the territory. A surplus typically gives no inherent bonus except for the stacking base trade good bonus; the main use of surplus trade goods is to trade them away to other provinces for commerce income, as well as to move the location (and bonuses) of the resource to another province. Imported trade goods contribute to the trade good surplus just like locally produced trade goods, while resources that are exported no longer give their effects to their province of origin.
Each trade good as a certain Base Trade Value that determines the amount of income countries receive from trading the resource. Trading common resources like grain or furs will give much less gold than valuable, exotic goods like dyes or gemstones. For foreign trades (i.e. between provinces belonging to different countries), the exporting province will receive the full base trade value, modified by the country's export value, in commerce income, while the importing province will receive 0.35 times the base trade value in commerce income, modified by the country's import value. Domestic trades will instead give only 0.20 times the base trade value for both the importing and exporting provinces. Areas that can produce and export valuable trade goods are therefore generally richer and more lucrative to conquer, but making sure that there are available trade partners is also important.
Trade route requests can only be initiated by the potential importer. Countries hoping to export resources should instead focus on making sure as many surplus trade goods are available as possible and if necessary make sure there are enough potential trading partners in diplomatic range, and then wait for trade requests to come in (which generally does not take too long).
Bonuses and effects
Each individual trade good has a particular bonus that is applied to their province, which stacks based on how many instances of the resource is present. Each category of trade goods has a different set of bonuses - military trade goods allow recruitment of the more specialized unit types as well as giving a small output or resource bonus, food trade goods increase the available in the province, and trade goods in each of the pop type categories increase the local happiness of the corresponding class. These bonuses can grow to be quite significant for large and prosperous provinces that produce and import many different trade goods, and are particularly important for providing the food necessary for more urbanized provinces that have long since outstripped their limited local food supply, as well as increasing the happiness of the normally restive nobles and citizens who produce most of the research points and trade routes in the country.
Each trade good that has a surplus in the capital province specifically also gives a special nationwide bonus. Unlike the normal province modifier, this bonus is not stackable and is only applied once per trade good, which means that it is generally better to have a large variety of surplus resources in the capital to accumulate as many bonuses as possible. As the capital province is likely to be the most populous province in any case with the most higher-class pops, it is almost always better to focus on accumulating trade good bonuses in the capital above every other province.
Changing trade goods
In general, trade goods cannot be changed directly by the player. Trade goods can, however, be changed indirectly with the foundation of a city. Agricultural trade goods ( grain, fish, livestock, and vegetables) can only be produced in settlements; founding a city on a food-producing territory will replace the trade good once the city is finished, typically with a higher value Nobles or Citizens trade good. The probability can be seen by hovering over the "Found a City" button at the "build" options panel. If the city status is later revoked, the territory will revert to producing its old agricultural trade good. Note that this applies only for cities founded during the game - revoking city status of a city that already exists at start will not change the trade good.
The trade good of a settlement can also be changed by a few special events and missions, most notably the prospecting task of the generic infrastructure mission.
Slaves & Tribesmen
Resources of this category grant mainly military bonuses, advantages or features. The production of cavalry in a province is linked to the availability of horses within that province, while the production of ships in a province is linked to the availability of wood within that province. Any lack of a strategic resource leads to a lack of a certain unit or advantage that may force the player to adapt his military strategy.
Use provincial trade routes to import goods to increase a pop type's happiness within the province. This works best in provinces with large numbers of the pop type.
Note the trade goods which increase happiness at the state level when the capital has a surplus:
- Slaves: Olives
- Tribesmen: Woad
- Freemen: Fish
- Citizen: Precious metals
- Nobles: Dyes
Food resources in a province help feed the pops of the province. If there is a surplus of food (food within the province, not as a resource for national or international trade), the pop growth rate increases. A lack of food leads to a decrease in pops and their happiness. Any lack of food can be prevented, by importing a food surplus from one province to a starving one. Any 1 surplus of a food resource within a province can be transferred within the player's nation by using 1 trade route.
Also, since creating a city removes Food-type Trade Goods from the settlement, such settlements should not be chosen to locate cities.
Military resources affect the quality of units and bonuses of military structures like forts. This type of resource does not change the variety of units the player's nation can build, but it does affect stats and advantages of produced units. Strategic resources should be preferred to military resources: With a hemp surplus in the capital, the ship damage increases about +10%, but missing wood leads to the incapability of building ships and of using the hemp-given advantage of additional damage.