Tibetan yak better tea - 酥油茶 Suyoucha.
Story has it that it derived from Tang dynasty princness 文成公主 Wen Cheng Gong Zhu, when she married Tibetan Royal(Chinese claim of occupation of Tibet might start from here). And she spread the tea drinking tradition.
Making yak butter tea undergo a delicate procedure. First tea leaves put and boil for tea juice then filter, and spice/yak butter inserted.
Spices used are walnut, sesame powder, peanut, watermelon seed, pumpkin seed, sunflower seed, egg, salt etc..
Drinking yak butter requires attention.
First hostess prepares a bamboo box in the middle and bowls. Then pours in order and shouts "hap tong! hap tong! (please drink tea in Tibetan)"
But never drink quickly, should drink slowly to let hostess know she has a great skill in making tea. Then hostess pours again. After drinking 3 bowls and if you don't want to drink anymore, then let her know by dropping tea leaves on the ground.
Then hostess won't pour you again.
Yak butter tea is a special tea only drunk on special occation. Normal days Tibetans drink 鹽茶 Yan Cha, a salt tea.