The Incas were a great South American civilisation. Until the sixteenth century, they ruled nearly 1 million square kilometres of western South America. Then they dissappeared. Not much each know about them because they didn't keep written records. But Reinhard has spent his life studying them. Before he found the three children on Llullaillca, he found fifteenth other Inca mummies on other mountains. he believes the frozen mummies were human sacrifices to the Inca gods.