In Buddhism, Amitabha, the leader of the Western Pure Land (Sukhavati) is red, so red is a symbol of power. In Tibetan opera, the character wearing a dark red mask represents a king.
The usage of red in Tibetan architecture is strictly regulated. It is mainly used in the outer walls of palaces, dharma halls, and halls for propitiating stupa towers, to show majesty. Thus it's one of the typical Tibetan colors. For example, the red palace of the Potala Palace has the shrine hall of the Dalai Lama's stupa towers, which is the center of the whole Potala Palace complex, with the important significance of commemoration and sacrifice. Most of the Dharma halls are painted in red, such as Nechung Kuten Hall of Drepung Monastery and Protector Deity Hall of Samye Monastery. In the primitive Bon religion of Tibet, the universe was divided into three worlds: god, man, and ghost. In order to avoid the invasion of ghosts, people painted their faces with red dye. With the development of the times and with the change of belief, this kind of red is no longer painted on the face but remains in the building.