Khipus (or quipus) were structured systems of knots used by the Inca people to communicate
numerical records. A relatively small number of khipus survived the Spanish conquest
South America and by and large are now held in museums. Structural details of each
of these khipus have been
described in a database by the Khipu Database Project
1. I have drawn the entity model shown here to describe this structure.
You can think of this model as a modern meta description of an ancient database system.
This model is adapted from a model of Khipu presented by the Khipu database
project and used to
describe the data tables held in their database.