Tam Đái

Tam Đái lay north of the Red River, between its broad plain and the hills rising towards Tam Đảo. The name was used for a prefecture encompassing several districts around Vĩnh Yên and the river junction at Bạch Hạc. In the tenth century, Nguyễn Khoan held Tam Đái during the struggles among regional lords before the consolidation of Đại Cồ Việt under the Đinh dynasty.

The later city of Việt Trì lies here.