Why has Tamil Nadu banned the Hindi language?

Tamilnadu has not banned Hindi but yes they resist the Hindi as common Indian language or language of instruction due to many reasons such as-

1. Anti-Hindi Agitation of the 1960s: The major turning point in Tamil Nadu's stance on Hindi was the anti-Hindi agitation in the 1960s. The central government’s attempt to impose Hindi as the sole official language of India led to widespread protests in Tamil Nadu. 

2. Cultural and Linguistic Identity Pride: Tamil Nadu has a rich cultural and linguistic heritage tied to the Tamil language, which is one of the oldest living languages in the world. 

3. Educational Policy : Tamil Nadu’s education policy emphasizes the use of Tamil as the primary medium of instruction in schools. This policy is part of the state’s broader efforts to ensure that the regional language is given prominence in education, which is seen as a way to foster better understanding and connection with local culture.

4. Practical Considerations: For many students in Tamil Nadu, Tamil is the language they use at home and in daily life. Using Tamil as the medium of instruction is seen as beneficial for their comprehension and academic performance. Introducing Hindi as the primary medium of instruction might create challenges for students who are more comfortable with Tamil.

5. Political Sentiments: Various political parties in Tamil Nadu have historically supported the use of Tamil and have opposed any measures that they perceive as promoting Hindi at the expense of regional languages. But sometimes also due to vote bank politics.

Tamil Nadu has not officially banned the Hindi language. However, there have been instances of opposition to the imposition of Hindi as a compulsory language in the state due to concerns about preserving Tamil language and culture. And now days in tamilnadu most of persons trying to learn hindi and in school it's is a compulsory subject.