Article from Los Angeles Times

Indigo Dye: An Ancient History
A 6,000 year-old fabric from Peru is the earliest known example of staining textiles blue.
By Deborah Netburn.  Saturday, September 17, 2016.

For the direct link, please go to:
http://www.latimes.com/science/sciencenow/la-sci-sn-oldest-indigo-dye-20160915-snap-story.html