The western, southern, and the northwestern parts are hilly and rich in vegetation. The Western Ghats and the Eastern Ghats meet at the Nilgiri Hills. The Western Ghats traverse the entire western border with Kerala, effectively blocking much of the rain-bearing clouds of the south-west monsoon from entering the state. The eastern parts are fertile coastal plains and the northern parts are a mix of hills and plains. The central and the south-central regions are arid plains and receive less rainfall than the other regions.