Nobody is completely sure at what time in old history the Pericu Indians lived on the Island of Magdalena, Baja California Sur. They were one of the three tribes found here by Cortes in 1535, when he came to the Peninsula of Baja California for the first time, and thought it was an island. These natives were very aggressive to white man, as they were forced to dress and go to live at the missions of the Jesuits. Of course, they did not like it, so those that lived on the islands fled, as soon as possible, back to their homes. One of the only remains to be found of their presence on Margarita Island are a series of huge shell middens, that must have been formed during thousands of years of consuming these molluscs always in the same place, and throwing the shells right there.

The better proof that these are real shell middens, made by the natives, is a series of rocks in a triangular form that fit the hand perfectly. That part of the rock that is to strike the shell of the mollusc is always damaged. The island is of a lovely fine powdery sand, so these rocks had to be brought from quite a distance to the mounds, the only place where they are found. Few Mexican archaeologists are interested in studying this material, as it is scarce, and lacks the attraction of finer and more numerous Maya or Aztec material!