Caral quipu.
Ruth Shady, an archeologist leading investigations into the Peruvian coastal city of Caral, said quipus were among a treasure trove of articles discovered at the site, which are about 5,000 years old. “This is the oldest quipu and it shows us that this society ... also had a system of “writing†(which) would continue down the ages until the Inca empire and would last some 4,500 years,†Shady said.What is really says is, A) the site actually nowhere near 5000 years old, B) that these quipu finds on the site are nowhere near 5000 years old and indicate a later reoccupation of the site, or C) that the continuity of 4500 years has been utterly lost in the archaeological record, or just happens to never have been found. I don't see C as a legitimate possibility.
granted, quipu are not referred to in this article, but age appears to be established:
http://www.philipcoppens.com/caral.html
Caral is indeed hard to accept. It is very old. Still, its dating of 2627 BC is beyond dispute, based as it is on carbondating reed and woven carrying bags that were found in situ. These bags were used to carry the stones that were used for the construction of the pyramids. The material is an excellent candidate for dating, thus allowing for a high precision.
The town had a population of approximately 3000 people. But there are 17 other sites in the area, allowing for a possible total population of 20,000 people for the Supe valley.
All of these sites in the Supe valley share similarities with Caral. They had small platforms or stone circles. Haas believes that Caral was the focus of this civilisation, which itself was part of an even vaster complex, trading with the coastal communities and the regions further inland – as far as the Amazon, if the depiction of monkeys is any indication.
For an unknown reason, Caral was abandoned rapidly after a period of 500 years (ca. 2100 BC).
Caral quipu.