Durga, According to Thiruthondar Puranam, Charaman and Sundarar came from Tiruvarur to Tiruvanchikulam and then proceeded to Kailash in `Iravatham' elephant. Only Sekkizhar's Periayapuranam (Thiruthondar Puranam) is authentic record of Sundarar's life and rest are just hearsay. Sekkizhar's Thiruthondar Puranam was composed in 11/12th century AD whereas Sundarar lived in 8/9th century AD. If Cheraman converted to Islam, Sekkizhar would not have written about him However Indian history says Islam came to Malabar region in the 7th century AD through traders. Kodungallur mosque is the first mosque built in India by Rama Varma Kulusekhara, the first convert to Islam Islam in India - Wikipedia, the free encyclopedia But Cheraman lived in the subsequent period say 8/9th Century AD and there is no evidence that he converted to Islam So there is no connection between Kodungallur Mosque and Cheraman. All the best