According to Taiji Qitian, one era for Heaven and Earth lasts for 129,600 years. This is divided into 12 epochs, each of which lasts 10,800 years.
以「太極氣天」來說，天地的一個階段、所謂「一元」的歲壽有十二萬九千六百年，如果分為十二「會」，則每一「會」的歲壽是一萬零八百年。