For thousands of years the people of the Andes have passed on their knowledge of color dying using natural materials found in nature. Today textiles are often a mix of both natural and synthetic fibers combining old and new traditions.
The Inca bag's fabric is boiled for varying periods, the yarn is dyed according to the natural materials used and the colour desired. Ingredients, like salt or urine are used to create multiple shades and colours, alter hues, or intensify colour saturation. After the yarns have dried, they are re-spun and made into balls of yarn. Materials and colors that are used depend on the region and personal preference of the dyers and weavers.
Such a wonderful thing to know that the Incas in South America are still preserving their weaving skills and knowledge.
INCA MARKET IN ECUADOR
A wide range of items with colors that go so well with authentic Inca Bags
Urine from children is carefully used to get different depths of colors. They are left to dry for several weeks before dying using them on the fabrics.
Boiling water is then used to get a variety of natural colors that blend well. 
Watch how Adelma demonstrates the procedure.
The Inca Bag on YOUTUBE