A high king is a king who holds a position of seniority over a group of other kings, without the title of emperor. Similar titles include great king and king of kings. The high kings of history usually ruled over lands of cultural unity; thus high kings differentiate from emperors who control culturally different lands, and feudal monarchs, where subordinates assume lesser positions. High kings can be chosen by lesser rulers through elections, or be put into power by force through conquest of weaker kingdoms.