Taien calendar

, 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.