The Deccan Plateau or the Peninusular India is a triangular table and separated from the Indo-Gangetic plain by Vindhya and Satapura ranges and impenetrable forests known as Dandakaranya and Mahakantaravana. The Deccan (meaning south) is flanked by the Eastern Ghats (Mahendra) and the Western Ghats (Sahyadri), which meet at Nilgiris (Blue mountain) with Dodo Betta peak at a height of 2,637 metres. Beyond it lie the Cardamom Hills, which may be regarded as the continuation of the Western Ghats.
There is a small gap about 35 kilometers wide, between the Nilgiri and Cardamom Hills, which provides an easy access from Coromondel coast to Malabar Coast i.e. from east to west which is known as the Coimbatore or Palaghat gap. Geologically the Deccan Plateau is older than the Himalayas and the Gangetic plain. The nucleus of the Peninsula is a triangular block of very old rock that cover its greater part from the Satmala - Ajanta ranges to the Nilgiris.
The Deccan plateau has a general elevation of 600 mtrs. and the general slope is towards south-east. The Peninsula narrows down towards the south and at last meet at Cape Camorin of Kanyakumari, the southernmost point of India. The Western Ghats is a continuous steep mountain wall running parallel to the shore of Arabian Sea for about 1140 kilometers and is 925 to 2475 meters high above sea level.
The narrow strip of land is generally 50 to 80 kilometers wide, but at places not more than 7.5 kilometers between the Arabian Sea and Western Coast up to Kerala. The area is highly fertile and rich with coconut trees. There are a number of flat-topped peaks, converted into impregnable fortresses, which played an important role in Maratha history.
The Eastern Ghats are irregular, scattered, broken and of much lower altitude than the Western Ghats. The land between the Bay of Bengal and the Eastern Ghats known as the Coromandal Coast is much broader than the Konkon coast.
The Deccan Plateau is known as Dakshinapatha and its inhabitants as Dravidians As a homogenous unit, isolated from the rest of India, it enjoyed centuries of peace, prosperity and plenty. Important ruling dynasties like Chola, Chalukya and Hoyasala have flourished here. The Sangam literature has enriched the literary traditions of the region. When Muslims invaded north India, the major religions of India, Hinduism along with Buddhism and Jainism sought refuge in the south and florished here.
The long coastline and the natural harbours of the Peninsula provided opportunities to the people for overseas trade and consequent colonization. They sailed to the South east Asia, Rome, Egypt, and Arabia for trade and commerce. Situated midway on the maritime routes between Africa and China it had brisk contact with both the sides and played an important role in the colonization of South-east Asia.
The principal rivers of the region, the Mahanadi, the Godavari, the Krishna (with its tributary the Tungabhadra) and the Kaveri flow into the Bay of Bengal whereas Tapti and Narmada flow westward and drain into the Arabian Sea. The Deccan is more dependent upon the monsoon wind than the northern plains, which has a number of rivers flowing from the Himalayas, where the melting snows supply water during the summer season. The Deccan rivers do not have this advantage.
The Narmada rises in Amarkantaka and flows westward through Madhya Pradesh, Gujrat and falls in the Gulf of Cambay. The Mahanadi originates in Amarakantaka and falls in to the Bay of Bengal. Godavari rises at Nasik in Maharastra and falls into the Bay of Bengal with tributaries such as the Wardha, the Penganga, the Waingaga, the Indravati and the Sabari. The Krishna rises near Mahabaleswar and flowing through Karnatka and Andhra Pradesh falls into the Bay of Bengal.
The river Tungabhadra is its main tributary, which again is the union of the rivers Tunga and Bhadra. Tungabhadra is one of the most important rivers of Indian history as it formed the frontier of the Chaluykyas of Badami and Kalyani, the Rastrakutas, the Pallavas and the Cholas. The Kaveri rises at Brahmagiri in Coorg and flows towards Bay of Bengal. Below Srirangam it divides into two : Coleroon and Kaveri. It is considered as the Ganga of South India.
The two halves of India offer striking contrasts in respect of race, language and social customs. Very few rulers of India were able to exercise political supremacy over both the regions. Occasional attempts by rulers like Asoka, Samudragupta, Ala-ud-din Khiliji, Mohammad Bin Tughlaq and Aurangzeb were made to bring the north and the south together under one political hegemony but in vain. The Arya-Dravida divide separates north India from south India since the beginning of Indian history.