In the 1300s, the bubonic plague swept through Europe killing millions of people. In the late 1400s, little flies swarmed Central Europe during the summers. To improve food sanitation conditions and allay fears of the return of the Black Death, some principalities in what is now Germany passed laws that required all food and beverage containers to be covered. A hinged lid with a thumb lift was added to the humble mug and an icon was born. Stoneware steins with pewter lids caught on and are still popular today.