Final answer:
The Incas used strings in the form of quipus as a portable, sophisticated system for record-keeping and communication, to manage economic relations and state affairs.
Step-by-step explanation:
The Inca Use of String in Quipus
The Incas most often used string in the form of an intricate device known as the quipu. A quipu consisted of variously colored strings, whereby the color, length, and the specific knots tied represented different kinds of information vital to the management of the Inca Empire. State officials utilized quipus for recording statistical data such as food production, taxes, warehouse inventories, and population metrics like births and deaths. The quipu's sophisticated structure allowed it to be highly portable, making it an ideal tool for communication and record-keeping across the vast expanse of the Incan territory.
Quipucamayocs were experts trained to read and interpret these quipus. Interestingly, the quipus' use extended beyond administrative purposes. It is believed that they could record not only quantitative but also qualitative information, such as ideas or even poetry. Despite the destruction of many quipus during the Spanish conquest and the loss of knowledge needed to fully decipher them, existing quipus continue to be studied, revealing the sophisticated and still partially understood record-keeping system of the Inca civilization.