Legends hold that Shu was the king of the South Sea, Hu was the king of the North Sea, and Hun Dun was the king of the center.
Shu and Hu often visited Hun Dun's kingdom, and Hun Dun always gave them a feast. To reciprocate his hospitality, they consulted with each other, saying, "Every person has seven apertures—eyes, nose, ears, and mouth—to see, hear, eat, and breathe, but Hun Dun does not have any. Let's drill the seven apertures for him."
They drilled one aperture each day. On the seventh day, they completed the seven apertures, but Hun Dun died.