Kvass or kvas (literally "leaven"; borrowe in the 16th century from Russian квас (kvas)), sometimes translated into English as bread drink, is a fermented mildly alcoholic beverage made from black or rye bread. It is popular in Russia, Belarus, Ukraine and other Eastern and Central European countries as well as in all ex-Soviet states, like Uzbekistan, where one can see many kvass vendors in the streets. Its origins go back 5,000 years to the beginnings of beer production.