Khipu

But a more searching analysis of some 450 of the 600 surviving khipu has called into question this interpretation. Although they were probably mainly accounting tools, a growing number of researchers now think that some khipu were nonnumerical and may have been an early form of writing.

Few of the world’s so-called lost writings have proved as daunting to decipher as khipus, scholars say, with chroniclers from the outset of colonial rule bewildered by their inability to crack the code.