For almost 1,500 years, the many trade routes known today as the Silk Road joined eastern China with western China, India, the Middle East, Europe, and the Swahili Coast of Africa. These trade routes created their own culture, uniting empires and connecting distant civilizations through trade goods like books, textiles, and precious substances. But the most important use for the Silk Road was immigration. Now, a new analysis of 2,000-year-old toilet wipes found near Dunhuang in western China has revealed that these immigrants traveled vast distances on roads maintained by the Han in 100 CE. Unfortunately, these wanderers brought their diseases with them.

In a new paper published this week in the Journal of Archaeological Science: Reports, a group of archaeologists in China and England describe how they found preserved fecal matter on wipe sticks used in a latrine at the Silk Road's Xuanquanzhi rest stop. Archaeologists excavated the rest stop roughly 20 years ago and discovered that it was one of many such oases maintained by the Han government during the early centuries of the Silk Road. Weary travelers with the right documents could stop there to refresh themselves and their pack animals. They could also, apparently, use the bathrooms. What made the Xuanquanzhi rest stop special was its location near the deadly hot Taklamakan Desert. The arid region has preserved countless treasures from the heyday of the Silk Road, including a bundle of sticks wrapped in rags near the Xuanquanzhi latrines.

While analyzing a collection of excavated goods from Xuanquanzhi, a group of archaeologists realized that these were no ordinary sticks. "These have been described in ancient Chinese texts of the period as a personal hygiene tool for wiping the anus after going to the toilet. Some of the cloth had a dark solid material still adhered to it after all this time," Cambridge anthropologist Piers Mitchell wrote.

In other words, the archaeologists had found a pile of toilet wipes from two millennia ago. They immediately scraped them off and sent the shavings to a lab for analysis. All it took was a glance through a standard microscope to see that some of these travelers had serious stomach cramps. Because the eggs of intestinal worms can survive for thousands of years, Mitchell said the research team was able to identify "roundworm (Ascaris lumbricoides), whipworm (Trichuris trichiura), Taenia sp. tapeworm (likely T. solium, T. asiatica, or T. solium) and Chinese liver fluke (Clonorchis sinensis)."

It's not surprising that people living in the second century CE were full parasites. But what caught the team's attention was the Chinese liver fluke, which is native to the marshy southern regions of China and could not have been contracted in the desert lands of Dunhuang. The person who pooped those eggs out, likely during a bout of extreme stomach cramps and diarrhea, had contracted them thousands of miles away.

Anthropologist Hui-Yan Yeh, who co-authored the study, said in a release, “When I first saw the Chinese liver fluke egg down the microscope, I knew that we had made a momentous discovery. Our study is the first to use archaeological evidence from a site on the Silk Road to demonstrate that travelers were taking infectious diseases with them over these huge distances.” Though historian Valerie Hansen argues that most people used the Silk Road simply to travel between towns, we now have proof that at least some of those travelers came a long way indeed.

The Silk Road was named in the 19th century by a German explorer, but it would have had many different names and routes during its heyday between 100 BCE and 1400 CE. The wipe sticks at Xuanquanzhi belonged to an early phase in the Silk Road's history, when the routes were controlled by soldiers and bureaucrats from the Han Dynasty. Later, during the sixth and seventh centuries, travelers simply called it "the road to Samarkand," referring to a massive trade city in what is now Uzbekistan.

Samarkand, home to the Sogdian people, lay on the western side of the Taklamakan Desert and was a melting pot of Chinese and Middle Eastern cultures. Later in the Middle Ages, the routes were repaired and controlled by the Mongols. The Silk Road was eclipsed by sea trade routes in the 15th century after centuries of dominating the imaginations of people from two continents and hundreds of cities. Its legacy remains so powerful today that even a sick traveler's wad of toilet sticks is a scientific marvel, yielding new insight into a great culture built on immigration and free trade.

Journal of Archaeological Science Reports, 2016. DOI: 10.1016/j.jasrep.2016.05.010