The khipu was a record-keeping device made from fibre strings that used knots to encode layers of information. They first appeared in Wari culture in modern-day Peru around 600 CE, and were later used across the Inka Empire. These remarkable, portable archives centralised and collapsed language, mathematics, history and accounting into a single object. So complex were the khipus that khipukamayuqs – or ‘readers of the knots’ – were trained specifically to decode them. Today, there are roughly 1,000 known khipus in museums around the world, varying greatly in both size and in purpose. And, as this video from the British Museum explores, these objects offer a remarkable window into pre-Columbian Andean culture and society – from military strategies to tax obligations – revealing much about the inner workings of the Inka Empire.