Pagan Kingdom
According to the chronicles, the Pagan Kingdom at first followed the prevailing Saka Pyu Era, but in 640 CE King Popa Sawrahan (r. 613–640) recalibrated the calendar, naming the new era Kawza Thekkarit ( ) with a Year Zero starting date of 22 March 638 CE. It was used as the civil calendar, while the Buddhist Era remained in use as the religious calendar.