Nachinarkiniyar , a commentator of ancient Tamil Grammar mentions this fact.
Silapaddikaram, one of the Five Epics of Tamil penned by the brother of the Great Chera King Cheran Chengkuttuvan, mentions this as well.
He was Illangovadigal.
So Thiruthani is not the place where Lord Murugan married Valli and it was Kumaran Koil.
IT is in the Western Ghats, down deep south in agreement with ancient landmass and Lankan chronicles call Murugan as Kattrama and Valli the consort of Murugan.
And Thiruveragam, the old name seems to fit Velimalai in Kumaran Koil.
So it looks as though Swamymalai is not Thiruveragam.
And Thiruthani is not where Murugan married Valli.