It was the third excavation in the pit - the first and largest of three pits at the site near Xi'an, capital of northwestern Shaanxi Province -- since 1974 when the terracotta army was discovered by peasants digging a well.
FIRST DAY: "BETTER THAN THOUGHT"
The new dig began at 1 p.m. Saturday, which marks the country's fourth Cultural Heritage Day, and it lasted about five hours on the first day.
"The most important discovery today is two four-horse chariots that are standing in tandem very closely," said Cao Wei, deputy curator of the Qinshihuang Terracotta Warriors and Horses Museum. "It is the first time for us to find such an existence in the excavation history," Cao said.
In addition, another important discovery was that a few newly-unearthed terracotta warriors were richly colored.
Archaeologists soon used plastic sheets to cover them for protection.
Richly colored clay figures were unearthed from the mausoleum of Qinshihuang in the Qin Dynasty (221 B.C.- 207 B.C.), the first emperor of a united China, in previous excavations, but once they were exposed to the air they began to lose their luster and turn an oxidized grey.
"From what we have excavated today, the preservation of the cultural relics is better than thought," said Xu Weihong, head of the excavation team.
"Take for instance, the discovery of the richly colored terracotta warriors gave us great confidence.
I believe the future excavation will go smoothly," Xu said.
The 230 by 62-meter pit was believed to contain about 6,000 life-sized terracotta figures, more than 1,000 of which were found in previous excavations, said Wu Yongqi, museum curator.
The State Administration of Cultural Heritage has approved the museum's dig of 200 square meters of the site this year, Wu said.
Also Saturday, deputy curator Cao told reporters that the state ministration has approved a five-year excavation plan submitted by the museum.
"We plan to dig about 2,000 square meters in the coming five years," Cao said.
NEW DISCOVERIES EXPECTED
Archaeologists hoped they might find a clay figure that appeared to be "in command" of the huge underground army, said Liu Zhancheng, head of the archeological team under the terracotta museum.
"We're hoping to find a clay figure that represented a high-ranking army officer, for example," he told Xinhua earlier.
Liu and his colleagues are also hoping to ascertain the success of decades of preservation efforts to keep the undiscovered terracotta figures intact and retain their original colors.
Most experts believe the pit houses a rectangular army of archers, infantrymen and charioteers that the emperor hoped would help him rule in the afterlife.
His argument is still not widely accepted by other terracotta experts.
The army is still known to most Chinese people as the "terracotta warriors and horses."
The army was one of the greatest archeological finds of modern times.
It was discovered in Lintong county, 35 km east of Xi'an, in 1974 by peasants who were digging a well.
The first formal excavation of the site lasted for six years from 1978 to 1984 and produced 1,087 clay figures.
A second excavation, in 1985, lasted a year and was cut short for technical reasons.
The discovery, listed as a world heritage site by UNESCO in December 1987, has turned Xi'an into one of China's major tourist attractions.