As a result, bilateral relations have their ups and downs and can be warm or chilly, euphoric or troubling. Even so, over the decades, the South Asian countries have learned to live and let live, regardless of the problems at home and across their respective borders.

The striving is to maintain friendly relations, a climate conducive for talks on matters of mutual interest and to prevent any situation from reaching breaking point. However, Tamil Nadu's political parties, despite being an integral part of coalition governments at the Centre for long years now, do not seem to have grasped this elementary aspect of diplomacy.

The Kazhagams – Jayalalithaa's AIADMK, Karunanidhi's DMK and Vaiko's MDMK – do their best to vitiate India's relations with Sri Lanka. The sideshows staged by these parties against India-Sri Lanka cooperation and against dignitaries (and ordinary citizens) from the island republic would be handy to illustrate a tract on "How to lose friends and alienate people".

It is bad enough that New Delhi is not good at making friends of India's neighbours. It is worse when the DMK and AIADMK push their sectarian agenda in external affairs and foment hostility to cultivate ill will.

Sri Lanka President Mahinda Rajapaksa's visit last week was yet another occasion for the Kazhagams to put up their predictable tamasha of protests – in the name of championing the rights of Tamils in Sri Lanka. The frontline performer this time was MDMK general secretary Vaiko.

President Rajapaksa, who laid the stone for a University of Buddhist and Indic Studies in Sanchi, held wide-ranging talks with Prime Minister Manmohan Singh in Delhi. Doubtless, devolution of powers to create conditions for Sri Lanka's Tamils "to live with dignity and respect", elections in the Tamil-dominated Northern Province and the political plight of Tamils after the LTTE's defeat in May 2009 were discussed between Singh and Rajapaksa.

A Comprehensive Economic Partnership Agreement (CEPA) and Indian fishermen being attacked by Sri Lankan navy were among the items on the agenda of the two leaders, who also met without their aides.