Inka Khipu (Inca Quipu)

There is no letter "k" in Spanish. The common spelling of these artifacts is Inca Quipu. Here is one explanation of the spelling change from Wikipedia.

Quipu is the Spanish spelling and the most common spelling in English. Khipu (pronounced [ˈkʰipu], plural: khipukuna) is the word for "knot" in Cusco Quechua. In most Quechua varieties, the term is kipu.

The use of the letter "k" is a phonetic convention. The Quechua have no uniformly accepted method of transcription. There are a number of English/Quechua Quechua/English dictionaries online and from what I could see, most of them use a standard Spanish transcription method. Here is a link to the Quechua alphabet. There is actually a Highest Academy of the Quechua Language or Academia Mayor de la Lengua Quechua (AMLQ), Quechua: Qheswa simi hamut'ana kuraq suntur. It is a private institution in Cusco, founded in 1990, concerned with the "purity" of Quechua.

The Khipu or Quipu is described in a Wikipedia article entitled, "Quipu." Here is a short description from the article.

A quipu usually consisted of colored, spun, and plied or waxed thread or strings made from cotton or camelid fiber. The Inca people used them for collecting data and keeping records, monitoring tax obligations, properly collecting census records, calendrical information, and for military organization. The cords stored numeric and other values encoded as knots, often in a base ten positional system. A quipu could have only a few or up to 2,000 cords. The configuration of the quipus has been "compared to string mops." Archaeological evidence has also shown the use of finely carved wood as a supplemental, and perhaps more sturdy, base to which the color-coded cords would be attached. A relatively small number have survived.

This photo was taken in the National Museum of the American Indian.