
Kolli Hills is a small mountain range located in central Tamil Nadu in India. The mountains are about 1000 to 1300 m in height and cover an area of approximately 280 km². The Kolli Hills are part of the Eastern Ghats, which is a mountain range that runs mostly parallel to the east coast of South India. The mountains are relatively untouched by tourism and still retain their natural beauty. They were sometimes known as "Kolli Moloi", the "Mountains of Death", due to the many diseases there such as malaria.
Tucked away between the Pachaimalai and Kalrayan hill ranges of the Eastern Ghats in South India, Kolli Hills (or Kollimalai, in Tamil) is indeed a remarkable spot in Tamil Nadu. Unlike man-made Ooty and Kodai, Kolli Hills is traditional hill country, the land of friendly tribes, and a part of the erstwhile kingdom of Valvil Ori, a Tamil king who was renowned for his generosity and valour. Formed in the shape of an open square, these hills were also known as Chathuragiri, literally meaning square-shaped hills.