Do you have a hand-tufted rug? Did you notice that there was white powder under it?
The white powder under your rug is latex, and its powdery mess is a common occurrence with hand-tufted rugs. Hand-tufted rugs are constructed from different parts that are "glued" together. There is a canvas with the design mapped out that the wool strands are inserted into using a tufting gun. This is a quick and cheap way of making a plush rug with amazing colours and endless design possibilities. The industry still calls it and sells it as "handmade", but it's a far cry from the hand-knotted rugs, which are really constructed by tying each individual knot by hand.
Once the design is complete, they coat the canvas with latex and attach a cotton backing to the rug. The problem with hand-tufted rugs is, that they don't last for a long time. While hand-knotted wool rugs can withstand the passing of years, latex can't. Sooner or later it will start breaking down and that's the powdery substance you see under your rug. It is harmless, unless you're allergic to latex, but it can be annoying. Simple vacuuming will keep it in check. You can also turn the rug upside down and vacuum the back once in a while. Using a rug pad will also help keep the powder away from your floors.