Seoltang is the local trader's language of Kelfour's Landing, which was widely used in I.C.E. Age GemStone III. It is not a full language in its own right. Merchants would string together phrases in Seoltang and use hand gestures to bridge gaps of meaning. Many of the archaic names used in the game were actually meaningful when translated out of Seoltang, which itself loosely meant "the selling language." It is the only language the Kral will use to communicate with outsiders, because their own language is too incomprehensible and idiosyncratic to be translated. They learn it from their slaves.
It is not clear how old the language is or its etymological roots. For example, Quellburn was presumably named over six thousand years ago in the Wars of Dominion, which was founded by refugees from Zor. "Quells" itself is a stultified form of the high Zori language, spoken by the Spider Temple zealots, that was used by the Council of Mages who ruled the kingdom. It might be the case then, implicitly, that Seoltang is also a degenerate form of Zori. Quellbourne translates as "freezing lands", for instance, but also means "land of the silver mist." It would make little sense for a kingdom to name itself in an incomplete pseudo-language instead of its own tongue. However, the Seoltang word parts often have obvious counterparts in the common language, such as "sma" meaning "small" or "blo" for "blown."