Milk continues to be a very important part of the Mongolian diet. The milk that Mongolians drink comes from many sources including cattle, camels, horses, yaks, goats, and sheep, though milk from cattle is now the norm. An old tradition among many Mongols was to not drink water straight. This could have been a result of the Mongols' belief that water was sacred. During the mid-thirteenth century, a Franciscan friar,
William of Rubruck, set out to the Mongol Empire to make an account of the Mongols. In his account, Rubruck noted the Mongols' drinking habits with water, saying that the Mongols were "most careful not to drink pure water". In a land where juice and wine were not readily available, many Mongols opted to drink milk-based products like suutei tsai or
airag (a type of milk alcohol made from fermented mares milk) instead of pure water. ==Popularity==