In ancient China, decorated ritual disks known as bi were made of jade and other materials. Archeologists have unearthed many glass bi in Hunan and other provinces. A document of the Warring States Period includes this reference: “to pay tribute to heaven with dark green bi.” This indicates that bi were ceremonial objects, but archeologists have determined that they were used mainly as decorations to be buried with the dead. Earlier bi are small and thin, while later disks are large and thick. The size of a bi indicated the social status of a tomb’s occupant. Bi and other excavated glass objects provide solid evidence of glassmaking in China from the fifth century B.C. onward.