With the help of an expert weaver, archaeologists have unraveled the design secrets behind the world’s oldest pants. The 3,000-year-old wool trousers belonged to a man buried between 1000 and 1200 BCE in Western China. To make them, ancient weavers combined four different techniques to create a garment specially engineered for fighting on horseback, with flexibility in some places and sturdiness in others.

The softer side of materials science

Most of us don’t think much about pants these days, except to lament having to put them on in the morning. But trousers were actually a technological breakthrough. Mounted herders and warriors needed their leg coverings to be flexible enough to let the wearer swing a leg across a horse without ripping the fabric or feeling constricted. At the same time, they needed some added reinforcement at crucial areas like the knees. It became, to some extent, a materials-science problem. Where do you want something elastic, and where do you want something strong? And how do you make fabric that will accomplish both?

For the makers of the world’s oldest pants, produced in China around 3,000 years ago, the answer was apparently to use different weaving techniques to produce fabric with specific properties in certain areas, despite weaving the whole garment out of the same spun wool fiber.