Province Building 1 (Military Ressources)

Some provinces have a stragetic ressource that allows you to recruit better units and/or agents, accelerates your research, raises the town wealth, lowers your building costs or contributes in another way.

Military ressources:
> War horses <
This ressource provides you with superior horses and therefore with a better charge for all your cavalary units (and infantry).
To use this resource and the castle to its full capacity you should use the following tree to build in these castles:
Stable - Katana - Yari - Encampment (Proving Grounds/ Armory/; depending on your own preferences).
I do not recommend to recruited Archers here or bow cavalary because they do not benefit from the charge bonus. They should be recruited in a province with an artisan to benefit from more accuracy.

> Artisans <
This ressource provides you with superior bow maker and therefore with a higher accuracy for all your bow units. To use this ressource to its full capacity you should use the following tree to build in these castles:
Archery - Encampment (Hunters Lodge) - Temple - Stables.
Some prefer an Armorer (Encampment) over a Hunters Lodge.

> Smith <
This ressource provides you with superior melee weapons or superior armor. Usually all units benefit from a better armor since this is the only stat which doesn't raise with your units experience ( all the others stats do). All units with a low starting armor benefit strongly from a better armor (except the Naginata Samurai, they are already heavily armored). To use this ressource to its full capacity you should use the following tree to build in these castles:
Katana - Yari - Encampment (Armorer) - Stables (optional) - Archer (optional)

The Realm Divide

The Realm Divide is triggered on three different occasions:

1. Gaining a legendary fame with the current Shogunate by taking more than 15-18 provinces (number depends on difficulty)
2. Taking Kyoto in the first place
3. Being announced Shogun (after holding Kyoto for 4 seasons)

All three types of the Realm Divide trigger a penalty for all clans towards you. That means, making vassals or allies during each of these phases will cause a new penalty.
If you become Shogun before you hold the maximum provinces, then point one becomes obsolete. Taking Kyoto raises your fame to legendary immediatly and there is no going back.
The malus will stop counting at -200 against you and that will probably cause even your longest ally to turn against you in the end. New clans (or rerised) will not suffer of the Realm Divide penalty, but still tend to side against you, although your standing was "friendly".

So triggering the Realm Divide should be chosen wisely and needs a lot of preparation.

Note: If an AI clan usurpate the shogunate it will not suffer any penaltys and its allies will still be there