Songkran is described as the "traditional Thai New Year" and I understand that January 1st was only adopted as the official beginning of the new year in 1941. Does anyone know what sort of calendar they used when Songkran actually marked the new year and what it was based on?

None of my Thai friends seem to know which speaks volumes about the educational system here.

Google is your friend:

http://en.wikipedia.org/wiki/Songkran_(Thailand)

"Although the traditional calendar of Thailand like most of Southeast Asia uses a lunisolar calendar, the date of the new year was calculated on a purely solar basis. The term Songkran comes from Sanskrit "Sankranta" and means "a move or change" — in this case the move of the sun into Aries — Mesha Sankranti."

Thanks Andre. Not sure why my search didn't pull that up.