Common Telerin is the primordial tongue of the Teleri or Lindar clan of the Elves.
It split off Common Eldarin at some time during the Great Journey, which itself split off Primitive Quendian, the original language of all Quendi, or Elves.
Its descendants are the language of the Teleri of Valinor, as well as Sindarin, and the various Nandorin languages.
The language of the Teleri of Valinor was influenced by and in turn influenced Quenya, and these languages remained very closely related and mutually intelligible. One Telerin change was that where Quenya uses 'QU' (KW), Telerin typically uses 'P'.