Tam Phu is a term refering three of Saints in Vietnam Belief System. They are Thuong Thien Saint, Thuong Ngan Saint and Thuong Thoai Saint.
Thuong Thien Saint is mother of the sky who represents for vitality, core of life and happiness. She’s all way in red dress.
Thuong Ngan Saint is mother of forest, mountain. She’s in green dress.
Thuong Thoai Saint is considered creator of water, river, sea, pond, lake, lagoon. Vietnam is agriculture country in the past, their live sticked with wet rice. Farmers believe she take care their harvest and that’s the reason why they respect and pray her. She’s in white.