I reviewed Chris Given-Wilson’s contribution to the English Monarchs series, Henry IV, for the Journal of British Studies. I am impressed to learn that he is branching out into… Incan history. From Aeon:

Instead of writing, the Inkas’ principal bureaucratic tool was the khipu. A khipu consists of a number of strings or cords, either cotton or wool, systematically punctuated with knots, hanging from a master cord or length of wood; pendant cords might also have subsidiary cords. The basis of khipuaccounting practice was the decimal system, achieved by tying knots with between one and nine loops to represent single numerals, then adding elaborations to designate 10s, 100s or 1,000s. By varying the length, width, colour and number of the pendant cords, and tying knots of differing size and type to differentiate data, the Inkas turned the khipu into a remarkably versatile device for recording, checking and preserving information.

The main uses to which khipus were put were, firstly, to record births, deaths and movements of people, thereby providing an annual census upon which local labour, military and redistributive assessments could be made. They were also used to count commodities, especially the tribute payable by conquered provinces such as maize, llamas and cloth (there was no coinage). Maize, for example, might be represented by a yellow cord, llamas by a white cord, and so on. Early Spanish chroniclers and administrators were astonished at the accuracy of khipu calculations: according to Pedro de Cieza de León, writing in the late 1540s, they were ‘so exact that not even a pair of sandals was missing’.

Read the whole thing.