A pan-Slavic language is a zonal auxiliary language for communication among the Slavic peoples.
There are approximately 400 million speakers of the Slavic languages. In order to communicate with each other, speakers of different Slavic languages often resort to international lingua francas, primarily English or Russian. But since Slavic languages are closely related lexically and grammatically and are comparatively easier to learn when another Slavic language is already known, there have been numerous attempts to construct a more neutral auxiliary language that could act as a common language for slavophones. The earliest pan-Slavic linguistic efforts preceded academic knowledge and reconstruction of Proto-Slavic, which was likely spoken between 2nd century BCE and 6th century CE, from which all Slavic languages developed in following centuries.