"Pettah" or "Pettai" is a village or suburb located outside a fort in South India or Ceylon.
About thirty kilometers east of Chidambaram, the ancient temple-town in South India, is a village called Parangi-pettai. Located on the mouth of the Kaveri river delta, it was, no doubt a strategic location for the European Franks (Ferenghi / Parangi) who once established trading stations all along the Indian coastline.
The unusual thing about this Pettai is that it sits next to Pichavaram, one of the largest mangrove forests in peninsular India. The place is big - and beautiful!
According to the Puranas, it is in these mangrove forests (Thillai Vanam) that Shiva acquired many of the accessories depicted in popular iconography -- serpents as necklaces and waistbands, a tiger-skin shawl and the little demon, Muyalakan, on whose back he dances the Ananda Tandava.
Thillai specifically refers to a species of mangrove trees - Exocoeria agallocha. It also goes by a more sinister name: Blind-your-eye mangrove. The plant has a milky latex so toxic that it can turn you blind.
Oddly, the particular mangrove species is native to only Tamil Nadu coastline and in North-West Australia...why is that? And why is it that mangroves are widely seen along India's eastern coastline and not on the western side, along the Malabar-Konkan estuaries?
* TNAU - Mangroves of India - http://agritech.tnau.ac.in/forestry/forest_mangrove_index.html
* Kerala Forest Department - http://www.forest.kerala.gov.in/index.php?option=com_content&view=article&id=73&Itemid=199
* Wiki - https://en.wikipedia.org/wiki/Mangrove