It's not impossible to win silvio82, it just needs different tactics than Noble difficulty.
More city specialisation (i.e. make 1 city a commerce city, one city a military city... etc)
Field more troops so that you dont have AI's coming to steal your lands.
Develop your friends more - choose who is on your side and who isnt and stay with that throughout the game as much as possible.
Pick a leader you like and play with that leader repeatedly until you win!
Eventually, you will find Prince to be the same as Noble.