While Geoffrey Chaucer was writing The Canterbury Tales in late 14th century, the Inca scholars high up in the Andes were struggling to put their thoughts on paper, because the Incas—who were the largest, the most sophisticated pre-Columbian civilization to exist in South America, evidence of which can still be found in their monumental architecture, technology, urbanization, agriculture and complex societal hierarchies—had one embarrassing weakness: they didn’t have a written language.

The Inca people spoke Quechuan, but they didn’t have a script to write it down. So there are no written materials in that language. Everything we know about Quechuan is from records written by other cultures, especially the Spanish after their conquest of the Inca Empire. While Inca scholars failed to invent a script, they did develop an ingenious method of keeping record of information such as transactions, tax obligations, census records, dates, and possibly a lot more using a complicated system of threads and knots called a khipu or quipu.

An example of a khipu from the Inca Empire. The more elaborate versions contained up to 1,500 or more strings.