By some counts, at its peak, the Mongol Empire stretched nearly 31 million square kilometres, an area of land roughly the size of the African continent. But what did this Empire led by Genghis Khan eat during the long conquests over highland passes and treachrous mountains? And what could it have to do with a bunch of scientists from the Max Planck instiute of Geoanthropology, looking at the teeth of Tibetans buried thousands of years ago? This week, we travel to the Highlands of Tibet and uncover an alternate history of milk. We discover the lessons it holds as we understand the food choices of the places we travel to.