Re: how to make mongol to build ship and attack island.
The Mongols don't recruit any ships, because they are bankrupt. Their huge armies of heavy cavalry are perfect for stomping your army, but their upkeep cost is too big for the Mongols to handle. So, I am suggesting using the console to add money to your faction and then donate it to the Mongols. Keep in mind that you'll need to repeat the proces many times to let the Mongols rectuit any ship. However, each factions has varying probabilities of launching an amphibious attack. For example, England or Genoa almsot always attack islands, but for factions like Lithuania or France it's almost impossible. Unfortunately I have no idea how probable is for the Mongols to make an amphibious assault or how you can mod the probabilities.