Shi'idese
From Wookieepedia, the Star Wars wiki.
Shi'idese was the native language of the Shi'ido species from. Shi'idos venturing from their homeworld became quickly fluent in Basic.
Some xenobiologists were still discussing if there was a written form of Shi'idese as of 0 BBY. It was clear that Shi'ido easily learned to write and read other languages.
