Range of hills in Tamil Nadu state, southern India, an eastward extension of the Eastern Ghats in the northeastern Tamilnad Uplands. The Pachaimalai Hills, together with the Javadi, Shevaroy, and Kalrayan hills, separate the Cauvery River basin in the south from the Palar River basin in the north. Extending over approximately 5,200 sq mi (13,500 sq km), they form a discontinuous line of highlands