What was the main issue that led to the DMK's rise to power in Madras State in 1967?

Anti-Hindi agitation

In Madras State, which is now known as Tamil Nadu, a regional party called the Dravida Munnetra Kazhagam (DMK) achieved power by securing a clear majority. This victory came on the heels of the DMK's leadership in a widespread anti-Hindi agitation by students, protesting against the imposition of Hindi as the official language by the central government. Notably, this marked the first instance where a non-Congress party secured an independent majority in any state.