A group of China's famed terracotta warriors are going on display at the National Geographic Society in Washington, on the last stop of a four-city US tour.

The exhibition, entitled "Terracotta Warriors: Guardians of China's First Emperor," includes a group of 15 of the statues that were recovered from the tomb of emperor Qin Shihuangdi, who ruled between 221 and 210 BC.

It is the largest group of the warriors ever to be displayed in the United States, said museum director Susan Norton.

The statues, which include infantrymen, a chariot driver, archers and a cavalryman, are around six feet (1.80 meters) tall and weigh 300-400 pounds (200 kilograms).

"Every single one has a different face, hair, position or armor," said Norton. Experts believe that the individual statues' faces may have been based on the artists who created the figures.

Some of the warriors bear traces of their original colors, pigments that were made with minerals and mixed with egg whites or animal blood.

Discovered in 1974, some 1,000 warriors have been excavated from emperor Qin's tomb near the Chinese city of Xi'an, but there are believed to be another 6,000 still to be unearthed.

The statues, which also include figures representing professions ranging from musicians to court officials, were intended to serve the emperor in the afterlife.

The exhibition has already drawn crowds across the United States, with 215,000 visitors on its Santa Ana stop in California, 400,000 in Atlanta, Georgia and 260,000 in Houston, Texas.

The warriors promise to attract similar interest in Washington, with Norton telling AFP that 100,000 tickets had already been purchased in pre-sales.

The National Geographic Society, known for the photo-rich magazine it has produced since 1890, obtained special access to the exhibit thanks to a pre-existing relationship with China and the excavation team working at emperor Qin's tomb.

The National Geographic magazine was one of the first to send a Western photo-journalist, Lou Mazzatenta, to take pictures of the warriors in the 1970s.

"Because of this, there is a warm collaborative relationship between China and National Geographic and most of all between Xi'an and National Geographic," Norton told AFP.

Along with the warriors, the society will be displaying 20 "Level 1" artifacts, China's highest rating for items of historical rarity and importance.

Among the items on display are weapons, coins, jade ornaments, a bronze crane and swan and stone armor.

The exhibition will run through March 31, 2010, when the warriors will be returned to China.