Genuflection (or genuflexion), bending at least one knee to the ground, was from early times a gesture of deep respect for a superior. In 328 BC, Alexander the Great introduced into his court etiquette some form of genuflection already in use in Persia. In the Byzantine Empire even senators were required to genuflect to the emperor. In medieval Europe, one demonstrated respect for a king or noble by going down on one knee.