Around the medieval period, kilns began to be built on an incline. As a result, objects with rounded bottoms, such as sake bottles, were arranged on their sides in the kiln so as not to roll downwards. Without exception, pieces from the medieval period show evidence of being placed on their sides. Also known as funadokkuri “ship flasks” these were exceptional pieces that would not fall over even on a rocking ship. The older the piece, the larger the circumference at the base.