In South Asia, five countries have parliamentary governments, including Bangladesh, Bhutan, India, Nepal and Pakistan. Of these, three are federal republics (India, Nepal and Pakistan), one is a unitary republic (Bangladesh) and one is a constitutional monarchy (Bhutan). Two South Asian countries, the Maldives and Sri Lanka, have either presidential (Maldives) or semi-presidential (Sri Lanka) governments which are accountable to elected legislatures; and both are unitary states.

South Asia is the world's most populous region among constitutional democratic republics, with over 1 billion people living under democratic systems, compared to populations of 500 million people in the European Union, North America or South America. The three core countries of the Indian subcontinent, including Bangladesh, India and Pakistan, began their modern democratic experiment as part of the British Indian Empire, particularly with the legislatures of British India. Sri Lanka is the oldest democracy in Asia in terms of universal suffrage, which was granted by the Donoughmore Constitution in 1931. Today, fundamental rights are enshrined in the constitutions of all South Asian countries.

The vast expanse of subnational units in India and Pakistan share a common feature of parliamentary government. All the 28 states of India and 4 provinces of Pakistan are governed by legislatures. Despite the extensive democratic framework, there are significant deficits and challenges to democracy, including human rights abuses, militarism and authoritarianism. Moreover, there is little cooperation between parliaments in the region. The state and provincial governments of India and Pakistan hardly have engagement with neighboring countries like Bangladesh, Sri Lanka and Nepal. Regional and local governments in unitary countries like Bangladesh and Sri Lanka also lack relations with regional counterparts in their neighboring countries.