Origin of the name
The Mountain is named Kolli Malai behind the name of Goddess Ettukkai Amman(KolliPaavai).
The Kolli Hills are featured in several works of classical Tamil literature such as Silappathigaram, Manimekalai, Purananuru and Ainkurnuru. Mahavidwan R. Raghava Iyengar in the research monograph Araichi Katturaigal has given exhaustive references to Kolli Pavai from early Sangam literature, concluding that the image is in Kolli Hills. The region was ruled by Valvil Ori around 200 A.D., who is praised as one of the seven great philanthropists of ancient Tamil Nadu. His valor and marksmanship are sung by several poets, and his exploits are a popular part of folklore. Ori is said to have killed a lion, bear, deer and a boar with a single arrow. The hills are said to be guarded by Kollipavai also called as "Ettukkai Amman", the local deity. According to legend, the sages chose Kolli hills when they were looking for a peaceful place to do their penance. However, the demons invaded the hills to disrupt the penance when the sages began their rituals. The sages prayed to Kollipavai, who according to the myth, chased away the demons with her enchanting smile. The KolliPavai hills is still worshipped by the people here and her smile is revered. The mountains have several mythological legends associated with them, and often come across as an eerie place in contemporary tales due to the unexplored and less traveled terrain. even at some places one can hear the presence of saptha kannigal. This mountain is full of herbs which retains health and vigour.
The Kollihills became taluk and forms a part of Namakkal district. Semmedu is the headquarters for the Kolli hills and Semmedu is connected by road to Namakkal and Salem. Nowadays the Bus service is provided up to Arappulishwarar Temple. BSNL (earlier DOT) established the first Telecommunication networks (LDPCO) in 1977 and after wards the Telecom facilities are continuously expanded depending upon the requirements at Kolli hills.
Farming and Vegetation
Apart from its historical significance, the mountains are covered with evergreen forests, but increasing areas of forests have been cleared for farming. Important farm products of the mountain ranges include coffee, tea, jackfruit, pineapple, black pepper and other spices. Rice and other minor millets form the staple food of the tribal people who inhabit these mountains. The jackfruit grown on these mountains is well known for its taste and fragrance and is often soaked in wild honey that is also harvested from these mountains. The mountains are covered by lush green vegetation in the spring and monsoon, and are streaked with streams which add to the natural beauty. There are three reserve forests that are controlled by the Government of Tamil Nadu, namely Ariyur Solai, Kundur Nadu, Pulianjolai.The yoke is still alive in these place. very power full thabasi is alive in koli hills.
The mountain is a site of pilgrimage, because of the Arapaleeswarar temple, which is believed to have a secret path to the Shiva temple in Rasipuram. This Shiva temple is said to have been built by Valvil Ori in the 1st or 2nd century when he ruled this area. "Arappaleeswara sathakam" is a poem which praises Lord Arappaleeswarar. It is believed that this temple existed during the Sangam period itself. According to legend, the shiva linga in the temple was found when a farmer was ploughing his land. It is said that the farmer accidentally hit the shiva linga while ploughing, and that led blood to ooze out of the statue. The small wound is said to be visible on the shiva linga even today.
Two viewpoints - one at Seekuparai and another at Selur Nadu - are being developed to encourage tourism. As of 2007, creation of a park and formation of an approach road to the Seekuparai viewpoint were nearing completion. The government maintains a pineapple research farm where hybrid varieties are created. Research about medicinal plants is also pursued on these mountains.The government holds a tourism festival in August.
Kolli Hills has been the top choice for nature lovers, hiking enthusiasts, trekking clubs and meditation practitioners among hill stations in Tamil Nadu. In comparison to other hill stations in Tamil Nadu, Kolli Hills is not commercialized, less polluted and offers unique mountain ranges.  Agaya Gangai is the famous waterfall situated near the Arappaleeswarar temple. Additionally the district administration has recently developed a botanical garden, Boat house, Cave house, New waterfalls called Masila Falls. The administration also celebrated "Ori festival" with lot of cultural events.. 
Kolli Hills and Surrounding Places
Under the foot hills of the Kolli Hills there are so many Small and Big Towns existing. From these places the Kolli Hills is visible in a panoramic view and the climatic conditions of these places is influenced by the climatic conditions of the Kolli Hills. Following are the few Towns surrounding the Kolli Hills: --- Namakkal, Sendamangalam, Kalappanaickenpatti, Belukurichi, SingalandaPuram, Rasipuram, Namagiripettai, Thammampatti, Mullukurichi, Koppampatty, Thuraiyur, Puliancholai, Thathaiyangarpet and all these places are well connected by frequent bus services.
People of Kolli Hills come down by foot with their produces to the foot hills of Kolli Hills and they sell their produces and go back after buying their required materials. This type of activities take place in few places like, Karavalli, Belukurichi, Pavithram, Thammampatti, and Puliancholai. People from various surrounding places of Tamil Nadu come to Belukurichi to buy the products of Kolli Malai.
Flora & Fauna
Forests here are extremely rich and diverse. Higher up the slopes, notable patches of tropical evergreen forests occur and the famous Ariyur Shola is one such. These forests are home to several species of endemic trees and plants. Kolli hills is said to have the largest expanse of evergreen or shola forest cover anywhere in the entire Southern part of the Eastern Ghats. Several coffee plantations, fruit orchards and silver-oak estates occur in this region.
Wildlife such as Sloth bear, barking deer, slender loris, Indian pangolin, jackals, mongoose, palm civets and many reptiles including endemic species like the lizards Hemiphyllodactylus aurantiacus, Calotes calotes, and snakes such as those of family Uropeltidae, the endangered Python molurus and a number of birds are found in Kolli Hills.
- R. Raghava Iyengar, Araichi Katturaigal, New Era Publications, Chennai, India (1987).
- Kolli Hills Tour Guide and Photos
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