Vietnamese calendar

After Vietnam regained independence following the third Chinese domination of Vietnam, the following dynasties established their own calendars based on Chinese prototypes, and every subsequent dynasty had appointed officers to man and create the calendar to be used in the realm.

[1] According to the Đại Việt sử lược historical chronicles, the Vietnamese rulers started building astronomical/astrological facilities in the capital Thăng Long (chữ Hán: 昇龍; i.e. modern Hanoi) as early as 1029.

The Chinese calendar is based on astronomical observations and is therefore dependent on what is considered the local standard time.

As a result of the shift, North and South Vietnam celebrated Tết 1968 on different days.

The title page lists the publishing date, "皇朝辛卯年孟秋上浣新刊" (Hoàng triều Tân mão niên mạnh thu thượng hoán tân san) on the right of the title (三千字解音).