Forbidden culture - hiding in plain sight

From the Times Online (UK) comes this account of travelling in Oaxaca and Chiapas during Day of the Dead festivities:

There’s a carnival feel to the way the Mexicans approach death, a sense of delicious expectation that the spirits of your loved ones will return to visit you if you tempt them with an offering of their favourite tipple. The atmosphere is not grave at all. For, if you believe that your ancestors are present in your everyday life, why should you be gloomy in remembrance of them? The Mayan Indians, who predominate in Mexico’s Chiapas and Guatemala, are highly spiritual and nominally Catholic, for the Spanish conquistadors imposed their religion on the indigenous people just as they imposed everything else. Every cemetery is a thicket of crosses; every village contains a church. The casual eye might mistake this for Catholic piety. But the Maya, who craft colourful masks to sell at market, have turned Catholicism into a mask of its own. From the outside, each church looks like a standard Spanish place of worship. Go inside, though, and you often discover that it is being used instead as a Mayan temple. In the church of Chamula, up in the mountains of Chiapas, the pews and altar have gone and the floor is carpeted with pine needles. Candles burn all over the floor. Dotted about are families who have paid a shaman to cure them. He feels the ill person’s pulse and then conducts the appropriate ritual: passing eggs in a pattern over their body, sacrificing a chicken and then spitting firewater or Coke over the dead bird, chanting prayers and lighting coloured candles.

While the article is definitely on the superficial side - it's a travelogue after all, not an anthropology piece - it does capture the feeling of old cultures surviving alongside (or, in some cases, under the veneer of) new. Travelling in Venezuala a decade or so ago, you could readily see similar tableaux - I forget the name of the coastal town we were in, but across the street from the church was a shrine to the Virgin Mary. Sort of. You see, the small grotto that surrounded her was built entirely out of full-sized conch shells - horned side facing inwards. I'll let you process that image for a while and come back when you're done. Back with me? With a picture? Hundreds of pinkish, shiny, vaguely oval-shaped slits... Seeing something of a fertility symbol are we? Good. At the feet of the Virgin(!), dozens of lit candles, fresh flowers, and freshly sliced oranges. I can no longer find the pictures we took, but I can say that the overall impression was quite striking. And across the street at the church itself? Nothing. At this point you're probably asking something along the lines of "WTF does this have to do with horror?". Not much, I suppose, except for this: a recurring theme in horror is the survival of ancient truths, of old beliefs dismissed as superstition. How many stories revolve around ancient curses, living gods, hidden cultures, or monsters from folklore? So - anyone else ever come across their own examples of old or suppressed cultures asserting themselves in defiance of the new and/or dominant culture? If so, care to share?