Yak
From Tardis Wiki, the free Doctor Who reference
Yaks were a type of bovine pack mammal native to central Asia.
Tibetans drank hot yak butter tea to fortify themselves against the cold of their native land. (DWM: Yonder... The Yeti)
The Fifth Doctor once bribed some sherpas with jelly babies to transport his TARDIS by yak. (BFA: The Roof of the World)
