For the ancient Incas, the khipus -- an accounting device that's crafted from knotted and colorful string -- is more than just for accounting. Historical accounts say that these unique tools are also used for communication, an alternative method of sharing history, biographies and letters that uses their own secret language. Imagine the stories behind these strings, the details of the civilization's history and culture that it could tell.

Unfortunately, this secret language has remained a mystery after all these years. Despite the best efforts of researchers, no one has been able to decipher the meaning behind the complicated combination of knots. Now, fresh clues may offer a glimmer of hope of finally understanding this ancient Inca language.

According to a report from the National Geographic, a pair of mid-18th century traditional khipus that has been kept hidden from outsiders in the Andean village of San Juan de Collata was recently made available to researchers. Spanish accounts said that Inca messengers delivered khipus instead of written letters, most likely to ensure secrecy during a time of rebellion against the colonial government.

Sabine Hyland, professor of anthropology at St. Andrews University in Scotland, explained that they found complex color combinations between the cords.

"The cords have 14 different colors that allow for 95 unique cord patterns. That number is within the range of symbols in logosyllabic writing systems," Hyland said.

One theory is that combinations of colored strings and knots may represent words or syllables.

The Collata khipus are bigger and more complex than the kind used for accounting. It's also made from hair and fibers of Andean animals -- which react to dyes better -- instead of the usual cotton. Locals told Hyland that understanding the khipus involves more than just looking at it. Touch also plays a significant part and it's necessary to pay attention to other features like color, fiber and direction of weave.

In ancient times, the Incas may have made thousands of khipus for correspondence and records, but fewer than a thousand remain today. A report from Asian Scientists pointed out that the technologically advanced civilization never developed a system of writing outside of khipus. Unraveling the mysterious code could reveal a huge chunk of the Inca history and culture, particularly during the colonial times.

Hyland shares her findings in a paper published in the journal Current Anthropology.