Wilds are areas of land you can conquer and they all give you different bonuses based on their level. The maximum level you can have for a wild is 10.=====
There are 5 different types of wilds that serve different purposes.
River- Increase in Food
Grassland- Increase in Food
Mountains- Increase in Iron
Hills- Increase in Stone
Woods- Increase in Lumber
There are other types of land including
Plains - Plains are used by players to build their additional cities on. The higher the plain, the more resorces and buildings the city will already have.
Bogs- Bogs are impenetrable. Bogs cannot be attacked or conquered