Till 1967, in India there was a single party rule. Even in States also there was a domination of Congress party. But, the scenario changed after 1967. Other parties started coming to power in the states.
There will be different party in the centre and in the states. Regional parties started entering Indian political system. From 1980's we can see the coalition government in the centre.
Congress last its domination and regional parties started participating in the national government. Therefore, coalition government started coming up in central. Many regional parties like TDP, DMK, Akali Dal, and AIADMK started playing their influential role. They started participating in government decision making.
Earlier, developmental work will go to those states which are ruled by Congress only. Because congress was dominating in the Centre. Now, the regional parties made developmental works come to their states. Because, they are also participating in the government planning process.
Whenever, central government is making policies it has to consider, the interest of the regional parties. Government planning and finance allocation is also influenced by regional parties.
Prescience of regional parties in national government sometime creating instability. Sometimes legislature is dissolved and fresh elections are held before the five year terms.
Regional parties are playing a major role in the Indian politics. Now, there influence is not only with respect to particular region but considered in national politics also.