the type of government you are able to build are depended by the place you want to build. For example the casse wouldn't be able to build a type 1 govermnent in India (a radical example but at least one I'm quite sure of). Now, the idea for the governments can be different from faction to faction therefor I'd suggest reading the descriptions of them (if you haven't done already) and I'm sure there is a piece about them in the faq. There also maps about this, I believe, in the map thread (one of the stickies) wich show wich governemtn can be built where.