Butter tea, or po cha, is considered by many the national drink of Tibet. This unique combination of black tea, yak butter, and salt give it a flavor that is closer to a soup than tea.
Butter tea is a drink that is common among the high-altitude regions of the Himalayas. It was invented sometime around the 7th century during the Tang Dynasty of China. The princess of China at the time married the king of Tibet. Soon after, trade routes were established that brought tea from China into Tibet. Tibetans use yak butter for a number of purposes so it is not surprising that it ended up being added to tea.