Since the 20th century, approximately 40,000 Han Dynasty slips have been unearthed at Juyan site. Their contents span from 128 BC to AD 283, covering nearly 400 years and providing invaluable material for studying the politics, economics and military affairs, and social life of the Han Dynasty.

The discovery history of the Juyan slips is also a story of efforts by scholars from China and abroad. In 1927,Swedish archaeologist Folke Bergman joined the Sino-Swedish Northwestern Scientific Expedition, and in 1930 he excavated over 10,000 wooden slips. Subsequently, from the 1960s to the 1980s, tens of thousands more slips were unearthed in large-scale excavations. Between 1998 and 2004, Wei's team discovered over 500 additional slips during archaeological work in Juyan.

"In the Badain Jaran Desert of Inner Mongolia, sandstorms can strip the paint off a vehicle," Wei recalls of one excavation experience."That day was sunny and bright, but suddenly the sky turned dark. A mountain of sand rolled toward us, and the vehicle was pounded. After more than 20 minutes, when the sandstorm subsided, we found the green paint on the rear window completely gone."

In this "sea of death", where annual rainfall is less than 40 millimeters, the archaeological team persevered for almost seven years.

What Wei remembers most vividly is a specially sized wooden slip found in the spring of 1998. "We found an old wooden stick in the rubble of a beacon tower. We gave it a kick, and it moved. When we pulled it out, it turned out to be a Han slip carved on six sides," he explains with a smile.

"It recorded that a soldier named Wang Xuan bought 170 bundles of licorice at one coin per bundle. Having no money at the time, he promised to repay the debt when he received his salary in the third month. This isn't just a cultural relic. It's clearly a 2,000-year-old pay stub and IOU!" Wei says.