The Sith language was the native language of the people of Ziost,Korriban, and Dromund Kaas. It was later expanded upon and evolved when the second generation of Dark Jedi split from the Jedi Order in 7,000 BBY, they were known as the Exiled Jedi, just after the Battle of Corbos. Even after the extinction of the Sith species, the language was preserved in Sith holocrons, temples, and tomes. The Sith language was written in hooked and barbed hieroglyphs. The language at that time was primitive in pronouncing the word structure. Therefore this language is incomplete to tie along with that aspect. There is also a lack of a great many modern language conjunctions, word structure and what not. It is a primitive language and was designed as such.