Passage: India is the world's most populous democracy. A parliamentary republic with a multi-party system, it has seven recognised national parties, including the Indian National Congress and the Bharatiya Janata Party (BJP), and more than 40 regional parties. The Congress is considered centre-left in Indian political culture, and the BJP right-wing. For most of the period between 1950—when India first became a republic—and the late 1980s, the Congress held a majority in the parliament. Since then, however, it has increasingly shared the political stage with the BJP, as well as with powerful regional parties which have often forced the creation of multi-party coalition governments at the centre.In the Republic of India's first three general elections, in 1951, 1957, and 1962, the Jawaharlal Nehru-led Congress won easy victories. On Nehru's death in 1964, Lal Bahadur Shastri briefly became prime minister; he was succeeded, after his own unexpected death in 1966, by Indira Gandhi, who went on to lead the Congress to election victories in 1967 and 1971. Following public discontent with the state of emergency she declared in 1975, the Congress was voted out of power in 1977; the then-new Janata Party, which had opposed the emergency, was voted in. Its government lasted just over two years. Voted back into power in 1980, the Congress saw a change in leadership in 1984, when Indira Gandhi was assassinated; she was succeeded by her son Rajiv Gandhi, who won an easy victory in the general elections later that year. The Congress was voted out again in 1989 when a National Front coalition, led by the newly formed Janata Dal in alliance with the Left Front, won the elections; that government too proved relatively short-lived, lasting just under two years. Elections were held again in 1991; no party won an absolute majority. The Congress, as the largest single party, was able to form a minority government led by P. V. Narasimha Rao.

Question: When did India become a republic?
1950