The dueling factions of Chivalry are the Agatha Knights and Mason Order. Both factions are native to Agatha. Chivalry: Medieval Warfare is set in the first civil war, showing the Mason Order's aggressive takeover of the country. Chivalry 2 is set in the second civil war, with the Agatha Knights now positioned as the rebels.
A third faction, the Tenosian Empire was added to Chivalry 2 in the Tenosian Invasion update.