The Taien calendar (大衍暦, Taien-reki), also known as Daien or Daiyan or Dayan calendar, was a Japanese lunisolar calendar (genka reki). It was developed in China; and it was used in Japan from about 746 to 857.
History
The calendar was created in China. It was first used in the 17th year of the Kaigen era during the Tang Dynasty.
The Taien-reki system corrected errors in the Genka calendar and Gihō calendar which were used in Japan in the first half of the 8th century. It was the work of Yixing, who was a Chinese astronomer.
References
Taien calendar Wikipedia(Text) CC BY-SA