Is this a Zapotec, Chimayo or Rio Grande rug?

Reading with interest the "is this a navajo rug" thread and remembered I had a rug (or maybe horse blanket) that I never identified ...Hadn't heard of Zapotec rugs but now curious as to whether mine could be one? No fringes, edge is folded over.

 

Beautiful rug, blooey. I am sure @Taupou will give us the best explanation, so I'll wait for Taupou.

 

It's Mexican, but not Zapotec.

It's a variation of a Texcoco design, named for the area where it originated, consisting of a central diamond, bordered by a (usually) white band (gray here), which contains the characteristic design "S" pattern. The "S" or "backward 5" supposedly dates back to a pre-Columbian image, and is usually one of the main features in identifying the style.

Originally the Texcoco rug was blue, black, and white, but today you'll see it in a number of color combinations.

 

Thanks @Taupou much appreciated!