 In different sects the three periods are known by slightly different names, variations originated by oral transmission of the teaching.The doctrine is especially important in the Xiantiandao group of sects, the most notable one being Yiguandao.The Three Suns doctrine places itself in a sect tradition ("Sanyangism", 三阳教 "Sānyángjiào", "teaching of the Three Suns") flourishing at least since the Ming dynasty.