After more than a year's excavation and research in northwest China's Shaanxi Province, Chinese archeologists have concluded that a large tomb belonged to the grandmother of Qinshihuang, the country's first emperor.

Zhang Tian'en, an expert with the Shaanxi Provincial Archeology Institute, said on Saturday that the tomb was chronologically the closest to the mysterious mausoleum of Qinshihuang, and was probably built on the emperor's orders.

"We are hoping that the excavation of his grandmother's tomb will help unravel the mystery about the first emperor's mausoleum, which still cannot be excavated. It will also contribute to research into Qin Dynasty burial culture," Zhang said.

Located under the new campus of the Xi'an Business College, the tomb is about 30 kilometers southwest of Qinshihuang's famous mausoleum. Qinshihuang united seven warring states and founded the Qin Dynasty in 221 BC.

The tomb is 550 meters long and 310 meters wide, covering 17.3 hectares.

Archeologists unearthed two carriages designed to be driven by six horses, which could only be used by kings and queens in the State of Qin.

The seals of court officials responsible for running errands on behalf of queens, queen mothers and princes, have also been found, said Wang Hui, an expert with Shaanxi Normal University.

The archeologists said the tomb belonged to Qinshihuang's grandmother, Queen Mother Xia.

According to Ding Yan, an associate researcher with the Shaanxi Research Institute of Cultural Relics and Archeology, the main tomb for the Queen Mother is 140 meters long, 113 meters wide and 15 meters deep, with the tomb chamber covering an area of more than 100 square meters.

Ding said that since the tomb was raided and burned several times, only fragments of Qin coins, grey clay vases and red clay boilers have been unearthed, as well as shards of decorative and ritual jade objects, broken pottery and pieces of bronze.

Sadly, Qinshihuang's grandmother's inner and outer coffins were also burned, Ding added.

The tomb is still under excavation.

Zhang Tian'en said that the Queen Mother lived until Qinshihuang was 20 years old and in the seventh year of his reign.

The royal lady is believed to have exerted considerable influence on the politics of the later years of the State of Qin and on Qinshihuang in particular.