Jodai Kayo (songs of the Jodai period) refers to the songs that were sung at festivals and at work, which evolved from shouts of joy and yells used to time or encourage activity.
感情の高まりから発せられた叫び・掛け声が次第に成長して、祭りや労働の際に集団でうたわれるうたとなったものを上代歌謡という。