This wildlands idea is a far better idea then the one I posted earlier in regards to slowing down pioneer and city spam. It would also move all the more difficult monsters into the wildlands making city placement outside of the wildlands far better.
Make it so that starting locations have enough room for one or two cities but after that the rest of the world is covered in weak, moderate, and strong wildlands that must be conquered in order to further expand. It would completely change the game play in a good way. No more mindless pioneer, outpost, city spamming at the beginning of games. And the act of taking territory seems like a lot of fun.
Make it so that monster lairs in wildlands produce a unit every x turns. Once the number of monsters in a wildland reaches y than z number of monsters will leave the wildlands in search of a fight. At the beginning of the game only weaker monsters will be sent out but in mid to late game more and more powerful monsters will form war parties and go a raiding. Thus the faster you conquer the wildlands the better.
The game should also insure that at least one weak wildland borders starting locations so that you, and AIs, have a direction to expand in. However the difficulty of all other wildlands in the game should be a decision made at world creation by the player with the following options:
The stronger the wildland conquered the better the fertile land/city build location(s), the better resources it will have and/or the better loot the monster lairs will have.
If you were to inter into a wildland it would be considered an act of war by the monsters of that wildland and they will actively try to destroy you. They will send monsters to attack your people and cities so don't inter into strong wildlands unless you are truly ready for that challenge. AIs should be programmed to not go waltzing into strong wildlands unless their armies/champions are strong enough. It would be sad to see the AI players taken out of the game because the monsters wiping them out do to the AIs stupidity in arousing the ire of the strongest monsters in the game.
This would also allow nations to increase their armies and champions level allowing each nation to have some strong units. The AI would need to actively insure that their units heal between battles by avoid combat until healed so that they can build up some high level armies. But if monsters inter into their territory they will use whatever forces they have available to take said monsters out even using damaged units. After all protecting their territory should be of higher priority then building up high level units.
By the time nations are bordering each other they will have each conquered a few wildlands, have multiple cities, and have experienced armies/champions. Thus when the game inters the final nation against nation phase it will be far more interesting. Overall this would make the game far more exiting and fun to play.
Just thought of something. If this was adopted then putting a unit into auto explore would be a bad idea unless auto explore avoided strong and moderate wildlands.