As of the 5.2 beta, you can no longer collapse into a horde. If you want to do this, it must be done in 5.1 or, heaven forbid anyone still uses it, 5.0.
I've not much to add other than if you want to try this, make sure you have one hell o a standing army before hand and place your capital next to where you want those religious rebels to come from to save yourself from batting them all over your country. 18 months after they occupy your capital, their demands will be enforced which includes changing your government to the government of the country they rose up in (not all government changes are possible here it seems)
I've not much to add other than if you want to try this, make sure you have one hell o a standing army before hand and place your capital next to where you want those religious rebels to come from to save yourself from batting them all over your country. 18 months after they occupy your capital, their demands will be enforced which includes changing your government to the government of the country they rose up in (not all government changes are possible here it seems)