The oldest national day in world history is San Marino's National Day. As far back as AD 301, San Marino made September 3 its national day. The term"National Day", originally referring to the national celebration, was first seen in the Western Jin dynasty. Our country feudal times, the national joyous event, is greater than the emperor's enthronement, the birthday and so on, therefore our country ancient times the emperor ascends the throne, the birthday calls"The National Day", today it is called National Day.