Kingdom

>Kingdom.
>Peninsula
>Mostly plains
>Lots of rivers
>Small mountain chain which is the border of the kingdom.

How would the economy look like?

Is there a mainland nearby?

Probably mostly fishing and light seasonal agriculture or forestry. It really depends on what the climate is like and what they can trade with their neighbors.

Ok, that really depends.

What sort of climate do they have? What are the growing seasons? Is it marshy? What sort of mineral wealthy is around? What kind of neighbors do they have? Where are they geographically in relation to other powers.

You have given us not nearly enough information to even begin postulating.

Depends on the size of the kingdom. A large one may be based on feudal agriculture, while a small nation could become rich through maritime trading

Germany-Spain/Denmark/Sweden...your choice.

Mostly agrarian with some mining operations in the mountain chain.

France or Germany depending on the distribution of the rivers.

Farming and trade

The most important element: Are these rivers navigable?

Also, how fertile is the ground?

Salt mining as punishment for political prisoners

Germany and Scandinavia are all heavily forested and Spain is very hilly. Maybe italy but most of the south is quite hilly iirc.

Germany has a lots of rivers. It is also part of the Great European Plain.

All of Italy is hilly.

That's fucking Italy.

a really boring place i don't wanna visit

Sounds like perfect farmland, so probably entirely agrarian

So a flatter Italy? Lots of farming. Every square inch of arable land would have farms. Protected from the north by mountains and on all sides by sea, this kingdom could become quite powerful and support a substantial population.

Maybe limit them somewhat by a lack of a resource. No iron or copper to be found, perhaps. Or too much rain sometimes, or not enough. Seasonal flooding or monsoons could destroy crops too to limit the land's potential.

Sounds like Denmark or possibly a more bumpy version of The Fens.

You forgot TEMPERATURE.
THAT'S LIKE THE MOST IMPORTANT DETAIL.

Please have canals and canal boats instead of railways and huge roads.

What climate?

Temperate

There are a lot of different climates that are temperate

>temperate plains, well-watered by rivers
Sounds agrarian
>sole land border has mountain chain
They won't need to expend many resources to military invasion, secure. However, the abundance of natural borders within the kingdom may lead to a lack of internal unity.
>peninsula
Probably a decent fisheries industry, and maybe access to trade routes by sea

Rivers flow from high to low, so they'd have plenty of stone shipped on rafts from quarries in the mountains. I imagine it as a feudal society, with the monarch less powerful in the grand scheme of things than the local lords. Lots of stone buildings and castles, the knightly caste legally owning the land and using serfs to work it. The sailors are the "freest" members of this society, since on the sea the landowning caste is less able to control people. The kingdom is likely fairly wealthy, due to its natural advantages.

>Rome

Korea, so a lot of agriculture, sale of herbs or spices abroad.

Honestly a better analogy than Italia or Spain,thesr are way too dry.

>Kingdom
Alright, that tells us very little other than "not a republic or theocracy"

>Peninsula
>Small mountain chain which is the border of the kingdom.
Which means that it's easy to defend

>Mostly plains
Alright, so easy to work/pass through

>Lots or rivers
Alright, fertile soil.

Some questions you may want to ask yourself
>Where is this peninsula located relative to the rest of the world?
>What rare resources are (or aren't) in the land?
>What's the climate like? You said it's temperate but is it on the hotter or on the colder side? More like Italy or more like Southern Sweden?
This tells us what the economy is like. If the peninsula is on the edge of the known world and has a Mediterranean climate and no significant resources, we're looking at a mostly agricultural based economy. If the peninsula is in the middle of the known world (perhaps in the middle of an ocean that splits two or three continents), in a colder region and has a lot of rare ores, we're looking at a more trade oriented economy.

Resources and geographical location matter, mate. Constantinople wouldn't be half of what it was if it weren't very conveniently located between Europe and India, same for Persia in general. Rome and Greece being more civilized in the Classical era than Spain probably has a lot to do with Spain being relatively isolated while Italy and Greece were far closer to entities like Persia or Egypt, aiding the spread of new ideas. A peninsula filled with rare spices and a peninsula with nothing special in it will be very different in terms of trade power. You've already told us a lot with these facts, but we need to know a bit more.

Agriculture, tourism, and methamphetamine production.

Almost all of Italy is hilly.

>How would the economy look like?
Mostly plain.

This. Also shipping most likely, no matter what the climate, if the peninsula is of any size - even if it isn't too near to other kingdoms or trade routes, it will probably be faster to ship things than take them over land.