The dye that makes blue jeans blue has been around a lot longer than anyone thought. Archaeologists digging in Peru found a piece of cotton fabric dyed with indigo that is 6,200 years old, according to a press release. That's 1,500 years older than the previous oldest discovered use of indigo from Egypt. And Live Science reports the Peru textile predates even the oldest known reference to indigo dye in the Middle East by 1,200 years. "Some of the world's most significant technological achievements were developed first in the New World," professor Jeffrey Splitstoser says in the press release. "We may well not have had blue jeans if it weren't for the ancient South Americans."
The indigo-dyed textile is made of what is now known as Egyptian cotton. It was found during a 2009 dig at a site in Peru called Huaca Prieta. According to a paper published Wednesday in Science Advances, it was intact thanks to "unusual circumstances of preservation" at the site. The fabric was embedded in a concrete-like substance used to build what researchers believe was a temple. Indigo is a notoriously difficult dye to make, as it requires the leaves of various plants to be fermented, then aerated, and then doused with an alkaline substance—usually urine in ancient times. (A newly discovered Nazca Line in Peru depicts a weird creature.)