Sian Ka'an ("Origin of the Sky") is a protected natural area that covers 528,147 hectares and is a Unesco World Heritage Site. Sin Ka'an is located only a few kilometers from Tulum. In pre-Hispanic times, it was governed by the Mayan tribes of Cohuah and Uyamil. Researchers have inventoried 23 Mayan Archeological sites within the reserve, with the ruins of Chenchomac, Chunyaxche, and Muyil standing out. These ruins can be visited during the tour of the canals that criss-cross this idyllic place. Human remains, pottery, statues, and tools dating 2300 years back have been found within the confines of Sian Ka'an. This reserve is a natural sanctuary for pumas, "tapires", "tlacuaches", toucans, white and caguama turtles, and endangered species, such as howler and spider monkeys, jaguars, anteaters, ocelots, "tapires", and even dolphins and manatees. The wetlands of this reserve are also home to a vast and well-kept population of crocodiles.