An ancient Buddhist temple and various other structures have been found in a tiger reserve, during the first expedition to the area for 84 years.

The Archaeological Survey of India (ASI) revealed pictures of the ancient caves and temples on social media, showing the remains of Buddhist structures with mural inscriptions on them. The temples were found in Bandhavgarh Tiger Reserve in Madhya Pradesh, the largest state in central India. The reserve is located around 300 miles from the Madhya Pradesh state capital, Bhopal.

"An ASI team covered nearly 170 sq km [66 square miles] falling in the area of the Bandhavgarh Tiger Reserve over months-long exploration of the region which was undertook for the first time since 1938," the The Archaeological Survey of India wrote in a tweet.

"In an exploration 26 temples, 26 caves, 2 monasteries, 2 votive stupas, 24 inscriptions, 46 sculptures, other scattered remains & 19 water structure are recorded," another tweet said.

"The time period of the findings covered the reigns of the kings Shri Bhimsena, Maharaja Pothasiri, Maharaja Bhattadeva. Places deciphered in the inscriptions are Kaushami, Mathura, Pavata (Parvata), Vejabharada and Sapatanaairikaa."

The reigns of these kings are thought to have occurred between the 2nd century and the 5th century, making the ruins at least 1,500 years old. Stonehenge in the U.K. is an estimated 5,000 years old, while Egypt's Giza Pyramids are around 4,500 years old, in comparison.

The inscriptions of older cities like Mathura and Kaushambi surprised the archaeologists, as these cities were located in Uttar Pradesh, another Indian state.

"Names of these cities located far away from Bandhavgarh suggest that there were trading ties and people from other cities may have donated something, but again, it is a matter of conjecture," one senior ASI official said at a press conference at ASI headquarters in New Delhi.

No other expeditions have explored this area since the 1930s, with this team gaining special permission from the forest district to explore the ancient structures.

"This is the first time ASI has explored Bandhavgarh since the 1938 exploration by archaeologist N P Chakravarti. Many structures there were documented. We reported and documented more structures, including ancient caves, temples, Buddhist remains, maths, sculptures, water bodies, mural inscriptions in old scripts like Brahmi and Nagari," superintending archaeologist of the Jabalpur Circle S K Bajpai, who led the team, said at the press conference.