That’s not true. Many other castes used to have their own thread ceremonies and wear it. In TN at least, I can think of the Chettiars and Nadars who did a 100 y

That’s not true. Many other castes used to have their own thread ceremonies and wear it. In TN at least, I can think of the Chettiars and Nadars who did a 100 years ago, and who rid themselves of it after concerted efforts by the Justice Party. Example: https://commons.m.wikimedia.org/wiki/File:An_elderly_Chettiar_Vellālar_wearing_the_sacred_thread_in_Sunnambukulam,_Tamil_Nadu._Photographed_during_the_Census_of_India,_1961.png https://commons.m.wikimedia.org/wiki/File:An_elderly_Chettia... Soundarapandian Nadar of Justice Party (and after whom Pondy Bazaar is named) campaigned in the Nadar community to get rid of the thread: https://alchetron.com/W-P-A-Soundarapandian-Nadar https://alchetron.com/W-P-A-Soundarapandian-Nadar Some Nairs wear it as well. Wearing the thread is not a “privilege” afforded to only Brahmins, although now in popular imagination it has become their identifier.