In 1974, a group of farmers were slowly digging a well in Xi’an, China, when one of them hit something hard with his shovel. As he continued to dig, he realized that he had discovered an ancient clay statue.
Archaeologists knew that China’s first emperor, Qin Shi Huangdi, had an underground mausoleum somewhere in the area. But the mausoleum was hidden on purpose after his death in 210 BC and the caretakers planted trees on top in the hope that it would never be found. But when archaeologists began to investigate, they realized that the clay statue was one of thousands buried just below the surface.
Called the Terracotta Army, there are no other burial sites which rival that underground army. And in recent years, new technologies have helped scientists understand how they came to be. Archaeologists have even discovered 20 more Terracotta Warriors in 2022
Scientists have not yet found all the soldiers buried with the emperor, but they estimate how much 8,000 statues make up this clay army. The statues were buried in three separate pits and include life-size warriors, officers and horses.
The soldiers wear uniforms which distinguish them from the officers. Horses wear harnesses and chariots have wheels with dozens of spokes. Some of the chariots are covered but with an open window, others are open air and have an umbrella to protect the driver from the sun.
The soldiers were deployed in battle formation, protecting the emperor in the afterlife. Scientists believe the workers started creation of the Clay Army when Qin Shi Huangdi ascended the throne at the age of 13 in 246 BC.
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As King of Qin, Shi Huangdi spent 25 years fighting and conquering rival states. After unifying China, he declared himself the first emperor. His dynasty ended just four years after his death, but the land he ruled over remained unchanged for centuries.
Some archaeologists estimate that it took about 700,000 artisans and workers to build the army over the years, and production stopped when the emperor died in 210 BC. They worked for nearly 40 years to build the army and experts suspect that many of these workers were enslaved people who were executed after their services were no longer needed.
There are many mysteries surrounding the clay army, and over the past few decades, new and non-invasive technologies have helped scientists understand how the clay army formed.
Building an army
Researchers used debris found among the statues to determine the material used to build the army. IN 2017 study in antiquity, scientists examined 12 fragments that came from warrior statues in pit 1, which is the largest of the three pits. They also examined examples of paving bricks and other statues, such as a figure depicting a palace acrobat.
They found that the statues were made with a non-calcareous clay paste that may have been from loess deposits, a type of siltstone that is common in northwestern China. The acrobat and warrior fragments also contain sand temper, meaning the sculptors changed the recipe at some point.
Non-invasive technologies allowed researchers to better understand the manufacturing process. IN 2021 survey in Archaeometrythe researchers used portable X-ray fluorescence spectroscopy to see inside the statues.
X-rays reveal different markings on the statues, “Gōng” (宫) and “Xianyang” (咸阳). They believe that these are the names of the two workshops responsible for the production of the clay army. The names help explain differences in clay sources and differences in clay paste.
Defense of defenders
Although the warriors were made of terracotta, the bronze weapons they held were real and well preserved. For years, scientists wondered if the creators had intentionally used an anti-corrosion agent to protect the bronze.
in 2019 article in Scientific reports, researchers were curious about the chromium found on the bronze and whether it was intentionally used to preserve the weapons. They analyzed samples of the weapons and the soil in which they were buried. They found that varnish was used to cover the clay warriors and it was rich in chromium. Over time, the varnish mixed with the dirt and the chrome spread over the bronze weapons.
Although chromium coated the bronze, researchers did not believe it was responsible for the preservation of the weapons. They suspect that the bronze was retained because of the soil’s moderately alkaline pH and small particle size.
The Terracotta Army was supposed to protect Qin Shi Huangdi in the afterlife, and now the warriors have their own protection. The site has been added inscribed on the United Nations Educational, Scientific and Cultural Organization World Heritage List in 1987, and a government-run museum manages and oversees the excavations as they continue.