How Tamil language became sem mozhi?

It's important to clarify that "sem mozhi" isn't a recognized term in linguistics or a description of any language. It's possible you're referring to a colloquial expression or slang term that you've encountered.

If you can provide more context or the original source where you saw this term, I can help you understand its meaning and explain how it might relate to the Tamil language.

For example, are you asking about:

* The history of Tamil as a Dravidian language? Tamil is one of the oldest Dravidian languages spoken in India and Sri Lanka. Its origins can be traced back to the ancient Sangam period.

* The evolution of the Tamil language? Tamil has undergone various changes throughout its history, including the influence of Sanskrit and other languages.

* The status of Tamil as a classical language? Tamil was officially declared a classical language by the Indian government in 2004.

Please provide more information so I can give you a helpful answer.