So you want to recruit vikings in your settlement eyh? Well it's not just a thoughtless process of creating barracks level 1 and start pumping those badguys out anymore!
In 785 the Baltic settlements' development were of different level and quality, but to enhance gameplay most settlements on our campaign map will start as a small village without any constructed buildings in it (other than crappy shacks as quarters). At the start of the campaign the settlements will have poor trade and 0 growth, representing the shabby living conditions and lack of infrastructure during the dark ages.
It will be your job as a leader to develop your settlements from a mere gathering of poor countryfolk into rich, influential hubs of power spewing out well-equipped (armor and weapon-wise that is...) vikings ready for war and pillaging.
So again, you want to recruit vikings? Well, to do that you will need a tool shed to provide tools for constructing buildings. Yes that's right, the pessimistic, gloom people in the Baltic hadn't even thought of creating a communal shack for tools until you showed up. (Notice from the picture above that all other buildings requires tool shed to be built.)
Right, so you have your tool shed. If you want to recruit vikings you will have to train them and supply them with proper armor and weapons... Vikings need leather armor and 2 handed axes!
To make leather armor for them you will need pelts, so a trapper must be constructed to be able to gather large quantities of animal pelts. Then you need someone to work the pelts... that would be the tanner. He will work those pelts into usable leather armor for your units.
Now for the 2-handed axes: First you must build a wood worker to efficiently provide wood, and then a charcoal burner to supply the smithy which in turn provides the 2 handed axes.
So now you have the equipment availiable, but your units need to learn how to use their weapons properly, how much their armor protects and how to fight in formation and follow orders. So you will need a longhouse to have a place to recuit and train regular countryfolk into battleready vikings.
As this process takes time you must sacrifice building trade and growth structures in favor of military buildings. If poorly managed you might very well go bankrupt unless you use your vikings to raid neighbouring villages... Which you will of course, that's why you wanted vikings in the first place, right?
Another part we have rewamped with the building tree is the size of the settlements, both population and upgrade levels. All of the settlements will start out as a village without walls and there will most likely not be possible to upgrade to stone walls in any settlement.
In addition to being historical accurate, this have some additional advantages in M2TW.
Firstly there will be much less prolonged sieges, especially in early campaign.
Secondly we won't see the hopeless pathfinding on top of the stonewalls and in castles sieges.