June 28 (UPI) -- Archaeologists have recovered the earliest evidence of plant-based textile dyeing. The evidence is a 3,000-year-old piece of cloth found in Israel's Arava desert.
Researchers say the record-setting wool and linen fragments offer insights into the textile industry that supported a highly hierarchical society in Israel's Timna Valley during between the 13th and 10th centuries BC.
"This was clearly a formative period, with local kingdoms emerging and replacing Egyptian hegemony in Canaan," Erez Ben-Yosef, an archaeologist at Tel Aviv University, said in a news release. "These beautiful masterpieces of weaving and dyeing -- the first evidence of industrial dyeing at the time, of wash-resistant color on textile -- support the idea of a strong, hierarchical Edomite Kingdom in Timna at the time."
The cloth is proof of two things, researchers said. First, the dyed cloth suggests society's elite dressed in manner befitting social status. Second, the cloth serves as proof of the significant wealth and trade connections needed to move textiles and other goods in and out of the desert.
To create the dye, colorful plants were cooked in water. The dye solution was then mixed with the fabric and mineral alums, which served as a fixative, encouraging the chemical bond between cloth and dye.
Gas chromatography suggests red dye was derived from the madder plant, while blue dye as derived from the woad plant.
"Both plants were known in antiquity as sources of organic dyes," said Ben-Yosef. "We know that these plants were used to create elaborate costumes during the Roman period, more than a thousand years later. Now we have evidence in the region of an Edomite society wearing textiles produced the same way, versus an earlier 'primitive' smearing of color on fabric."
The dyeing process required levels of water and materials that couldn't have been supplied locally, researchers say. Instead, textiles were likely imported from the Mediterranean.
The Timna Valley is famed for its copper ore deposits. Copper ore has been mined in the valley since at least the 5th millennium BC.
"We can make many inferences according to this discovery," Ben-Yosef said. "To force a large group of people to work in dangerous mines in the desert, you need a strong ruling party -- an elite that probably wore exquisite clothes to further distinguish themselves."
Researchers detailed their discovery in new paper, published this week in the journal PLOS ONE.