New research suggests that a plaster mixture composed of cannabis, clay and lime helped preserve ancient Indian paintings inside the famous Ellora Caves from degrading over the past 1,500 years. 

The Ellora Caves were built between the sixth and 11th centuries A.D. in the western state of Maharashtra, India. They are made up of a group of 34 temples carved out of stone and are dedicated to Buddhism, Hinduism and Jainism. Hemp samples collected from cave number 12 of Ellora were analyzed for the recent study. 

Researchers Rajdeo Singh, an archaeological chemist of the Archaeological Survey of India's science branch, and Milind M. Sardesai, who teaches botany at Dr. Babasaheb Ambedkar Marathwada University, found that the cannabis played a key role in preserving the World Heritage site, as it regulates humidity and deters pesky insects.

"The caves are breathtaking examples of rock-cut architecture that stands testimony to the imagination and artistry of its creators," Singh and Sardesai wrote in their study. 

Using a scanning electron microscope, infrared spectroscopy and stereo microscopic studies, researchers were able to isolate specimens of cannabis from the clay plaster. 

The remains of cannabis, commonly referred to as ganja or bhang in India, indicate that it was primarily used as an insulating agent and to strengthen the clay and lime mixture.

"Hemp was extensively used in Ellora as well as by the Yadavas, who built the Deogiri (Daulatabad) fort in the 12th century. Hemp was not used in the Ajanta caves, which are about 30 rock-cut Buddhist structures dating back to the 2nd century BC. Rampant insect activity has damaged at least 25 percent of the paintings at Ajanta," Singh said. 

What's even more remarkable about the find is that the preserving qualities of the hemp mixture found in the Ellora caves far surpasses that of any ancient plaster uncovered in the past. 

"Studies conducted in Europe suggested that buildings constructed with the use of cannabis sativa could last for 600 to 800 years. Ellora has proved that only 10 percent of cannabis mixed with clay or lime in the plaster could last for over 1,500 years," Singh added. 

Their study was recently published in the journal Current Science.