Ar-Adûnâim, who replaced Umbar from previous versions, start as a neutral horde nation, therefore they can choose where they will land and which side they will join - when controlled by A.I., however, they always land in Umbar and become aligned with evil. Additionally the Clans of Enedwaith faction starts with neither allies nor enemies and can therefore choose sides freely.
Wars between evil factions and more frequently between good ones are indeed not unheard of, either through AI choices or through scripts. an alliance must first be broken via diplomacy. This does not mean that the player cannot choose who to ally with and who to fight, but there are certain limits, e.g. This is the morality axis Tolkien himself based his legendarium on and Divide and Conquer stays true to this. There are 26 playable factions in this submod that can generally be divided into two groups: The 'good' factions and the 'evil' factions.
