Quipu
Knotted, coloured cords the Andean empires used to keep tax, census and storehouse records — data stored in string rather than script.
The Inca empire (roughly 1400–1532) had no writing system yet still had to administer a realm of millions. Its answer was the quipu: a main cord with pendant strings whose knots encoded numbers in a positional base-ten scheme. A knot high on the cord meant hundreds, lower down tens, at the bottom units — the same place-value idea as a counting board, executed in cotton and llama wool.
The record-keepers, khipukamayuq, were effectively the empire's accountants. Some scholars argue the most elaborate quipus also encoded narrative text, but that reading remains unsolved. Spanish colonists burned thousands as idolatry after the conquest, which is why so few survive and why the code is largely lost.