Traditionally Tulvan is believed to be derived from the word "tulv" a verb meaning "to think". This, of course, can't be so. Many have argued that the original meaning of the term for the language was lost through time. But that it most probably was related term Tuluan. In fact the Tulvan meaning connecting it to tulv is a popular etymology. Many have indicated remains of writings connecting to Tuluan and an even older term, Tuluanna, the meaning of which is now lost.
In any case as a people so very devoted to thinking and reason, it was natural to assume that both words would merge with time in what is now known as Tulvan. This is also increased by the fact that Tuluan wouldn't be implausible as a verbal derivation from tulv. But with discoveries about Tuluanna, the folkloric etymological origin of Tulvan is now not widely supported by professionals.