From the encyclopedia menu, select « Kingdom » and the one that interests you. To do this, select the faction that is near your territory and press N to open the game’s encyclopedia. The best way to increase your chances of survival is to bring other clans into your faction. In any case, imagine that you survived the war and are now the owner of your colony. However, there is a small chance that no one will declare war on you. Either way, you have to fight, because even if you are elected ruler, you will have to leave the current kingdom to establish your kingdom, which means that it will regard you as a traitor and declare war. Or, optionally, take any city under siege. To do this, join one of the factions and deserve to be elected as the head of the colony. To build your own empire, the hardest thing to do is get a deal available to you. However, the requirements to complete the mission are the same for both parties. Istiana wants you to support the existing kingdom and help the Empire, while Arzagos wants to destroy it. The location of these heroes will be marked with markers. After completing the first two tasks, you will need to meet Istiana and Arzagos. To establish your kingdom, you must first complete the story quest line.
Mount & Blade II: Bannerlord: How to Create Your Kingdom (Become King)
