The first Tamil movie I ever saw was Pennin Perumai (Woman's Pride), (1956).
It was presented as a classic film to the South Indian community in Boston, where I went to college. I was a beginning Tamil student, so I didn't understand much. Here's what I remember:
The heroine (Savithri) is married off to a rich man's son (Gemini Ganesan). After the wedding she discovers to her horror that he is mentally handicapped. [Extensive research on the Internet has revealed that his stepmother had given him something to make him sleep as an infant, retarding his development.] Being a noble Indian wife she sets out to teach him proper behaviour, reading and writing, etc. By and by he is cured, becomes a normal man, and they are in love.
Meanwhile, the hero's younger brother (Shivaji Ganesan), son of the rich man's second wife, is a villain - which is interesting, because Shivaji Ganesan was one of the top heroes in Tamil films in his day. He was still quite young - that's him holding the rifle in the picture above. I have no idea why he aimed a gun at his older brother, but I think that doing so shocked him into seeing the error of his ways…
More research informs me that the film was a hit, and ran for 29 weeks.
There's a strange reminiscence of the actress Savithri by her children