Dugu Xin (独孤信, A.D. 502 - 557) was a famous stateman of Sibo (鲜卑). Sibo was a nomadic ethnic group, and built a strong empire named "Wei" (魏) in A.D. 386. This empire was called "the Northern Wei" (北魏) by later people. Dugu Xin was born in a noble family of the Northern Wei Empire. In A.D. 534, the Northern Wei Empire was divided into two countries, the Eastern Wei (东魏) and the Western Wei (西魏). Dugu Xin became the most important minister of the Western Wei Empire because of his outstanding talent. He occupied many important positions of the empire. Every day he signed many orders and documents. If every position needed a seal, he must take many seals every day. Obviously it wasn't convenient. Accordingly, a unique seal which includes all of his positions appeared. This seal was made from a jet. It has eighteen sides, and there are the names of positions in fourteen sides.Dugu Xin's first daughter was the wife of an emperor of the Northern Zhou (北周) Dynasty; his fourth daughter was the mother of Li Yuan (李渊, the first emperor of the Tang Dynasty); his seventh daughter became the empress of Sui Wen-Emperor (隋文帝, the first emperor of the Sui[隋] Dynasty). But Dugu Xin didn't see the glory of his daughters, because he was forced to kill himself in the early days of the Northern Zhou Dynasty.The Unique seal is kept in the Historical Museum of Shaanxi Province.