The position was established in the Taihō Code of 702. The official acted in the context of a Council of State (daijō-kan) which was made up of the three men.
- the Chancellor or Prime Minister (daijō-daijin)
- the Minister of the Left (sadaijin)
- the Minister of the Right.
The Taihō Code system was replaced in the Meiji period.
Udaijin Facts for Kids. Kiddle Encyclopedia.