A jade cong is the Liangzhu culture object with a square body and a circular central hole, probably used in ritual contexts.
Cong were carved from jade into a distinctive form: the outside is generally angular or square, while the interior is a round tube. Many examples have repeated faces or mask-like designs arranged in horizontal bands.
The Liangzhu culture flourished in the lower Yangtze region from about 3300 to 2300 BCE. Its elaborate jade objects, large settlements, rice agriculture, and massive water-control works show a highly organized society.
Jade cong are often discussed alongside jade bi discs, but the shapes are different. A bi is a flat circular disc with a central opening, whereas a cong is a tubular object with an angular exterior. Their exact meanings remain debated because no written explanation survives from Liangzhu society.