The coffin was discovered in the field of Phú village, Ân Thi town, Ân Thi district, on November 26, 1997. The coffin dates to the period of 2,500–2,000 years ago. This is a unique burial form of the ancient Vietnamese people of the Dông Sơn cultural period. The coffin has a circular cross-section made from a large wooden trunk, which is cut into two parts. These parts are placed on top of one another. The inside of the coffin is very evenly cut and beautiful, while the the outside part has no trace of manipulation. The huge size of the coffin proves that its owner belonged to a wealthy, upper-class, and had a high social status. This is reflected in the old Vietnamese society divided into the rich and the poor which were eventually transformed into social classes.