Quipu

The
Inca recorded numbers and perhaps
other kinds of information on the knotted strings of a quipu.
Inca administrators used quipus to keep accounts of items
owned and in storage within their districts, such as agricultural
products and livestock. Unlike pre-Columbian civilizations
of Mesoamerica such as the Maya
and Aztec, the Inca had no form of true writing.
Werner
Forman/Corbis