The Triquis are an indigenous group that seems to be able to maintain their traditional dress and their language. Their very distinctive long red huiples (dress)makes them stand out. Their traditional homelands are in western Oaxaca, I took these photos in Tlaxiaco, about 2.5 hours west of Oaxaca city. But there are also Triqui women, still wearing their bright red huiples here in Oaxaca. The women are often involved in weaving and selling all sorts of textiles. I have heard that many of the Triquis now living in Oaxaca are women who have had to live their homes because of abuse and/or non support by their husbands. This fits with I have observed, very rarely does one see a man helping or accompanying these women as they go about their small businesses.
I met an interesting person when I was in Oaxaca last March who was doing some research on the Triquis. You can read some of her observtions here