Devadasi system :) but it's erased history at this point and I also didn't know about it growing up. For historical sources I'd recommend Domingo Paes's book on Vijayanagara empire and Chola inscriptions in the Tanjore temple.

You can also look up Bangalore Nagarathnamma, Veena Dhanammal, Mylapore Gowri ammal, Coimbatore Thayi, Balasaraswathi, Muddupalani. Some of them have books written on them.

If you'd like more sources, plz let me know -- I'll send some book titles your way.