Take a look at that 17th century Dutch map Kaart van Jaffanapatnam en onderhoorige landen en eilanden (Map of Jaffanapatnam countries and islands and dependencies). The manuscript is in the Nationaal Archief, Netherlands, but you can get a fairly large view at beeldbank.nationaalarchief.nl/na:col1:dat516410. Certain browsers let you translate the web page into English. Get it full screen and start spotting the Sinhala place names.
The first name to hit you is Welligamo. As one of the four main divisions of Jaffanapatnam, it`s written larger. No big news there. Everyone knows about Valikamam and Weligama, but everyone may not know the transition happened post 17th century. The real revelations are the smaller print locations Cottiewatte, Watane, Vimangamo, Walandale, Lilagamo, Tangode, Tambale, Batecotte, Anecotte, Naloer(Nal oya), Oergavature, Nagamoene, Tambegamo, Coylacandy (Kohila Kanda), Mepale, Pollopalle, Alipalle, Malwattoe, Anungay, Walewitakepoelo, etc. etc. These are just the ones that stand out without ambiguity to my naked eye on the computer screen. I`d love to have someone with an eye for handwritten script and etymological expertise subject the manuscript to a magnifying glass.
And yet, in essence all this is old news. H. W. Codrington for one would have yawned. (The place-names in the peninsula indicate that it was held by Sinhala inhabitants at no very remote date, - Chapter VI, Short history of Ceylon, 1926). I imagine he yawned from The Great Beyond in 1965, when the PhD student K. Indrapala highlighted the toponymic evidence involving over a thousand place names of distinctly Sinhalese origin `in Tamil garb` presented by the Jaffna peninsula. But then most people are not Codrington. For one thing, primary evidence such as the Kokila Sandesaya and the 17th century map impacts like a bullet between the eyes, while pronouncements by an expert, however respected, merely wait politely by your head for admittance. You can either take it or dismiss it as personal whim or idiosyncrasy of the expert. D. B. S Jeyaraj for example, responding to someone`s web comment about place name evidence went, oh place names? But that PhD thesis has been superseded now by the Indrapala 2005 . It`s nothing of the kind. 2005 Indrapala merely maintains an undignified and deafening silence about the whole place names motif.
I am pretty sure that even scholars specialized on 17th century Lanka would find Sinhalese place names in 17th century Jaffna a trifle odd. On a purely academic, bloodless level, they may know of the distinctly Sinhalese origin place names in Tamil garb thingy, but in their minds the `garbing date` would be long, long ago the mid 13th century or the 14th century at the latest. There is this surgical deadline drawn in the time stream of Lanka. By 14th century latest, all Sinhalese place names in Jaffna should be decently covered in Tamil garb, all surviving Sinhalese populations should neatly die by assimilation. A clean amputation followed by cauterization. A definite closure to the Sinhalese chapter of the peninsular.