Olys Corellisi, translated in itself as "Old Corellian" in Basic, was a language used by the early Humans on Corellia. As the Corellians began to interact with other Core Worlds over thousands of years, Basic words and phrases flooded the Corellian lexicon, forming the latter Corellian language. After over twenty thousand years of intermingling, Old Corellian nearly vanished approximately four thousand years before the Battle of Yavin. With the ascension of modern Corellian, Old Corellian became a relic preserved by linguists and conservatives wishing to remember the forebears of Corellian society.
The language was kept alive in two noteworthy groups: Corellian colonists and Corellian fringers. Corellian colonists that left their homeworld to settle other terrestrial planets were without the influence of Basic, such as the colonists of Socorro. The second group, made up of smugglers, thieves, con artists, and other fringers used the language as a code to communicate secretly during dangerous situations.
Sahsahlah = 'the promised land' or 'the place of wise fools', used in conversations when opinions differ and one party wants to indicate that the other will not get their way.
The Star Wars Adventure Journal #7 says that Old Corellian died out circa 4,000 BBY, but The Black Sands of Socorro indicates that the colonists did not depart for Socorro until nearly 3,000 BBY, leaving a questionable gap in the timing of Old Corellian's practical extinction.
Some Old Corellian words look like their respective Basic translations, or synonyms thereof. This is not surprising, if we assume that the Basic language has a vocabulary derived, in part, from Olys Corellisi, much like real-world English are derived from Old English. In other terms, the Old Corellian words could be seen as alternative ancestors of their respective English translations.