The Lhammas as published presents the theory that all the languages of Middle-earth descend from the language of the angelic beings or Valar, Valarin, and were divided in three branches:
Oromëan, named after Oromë, who taught the first Elves to speak. All languages of Elves and most languages of Men are Oromëan.
Aulëan, named after Aulë, maker of the Dwarves, is the origin of the Khuzdul language. It has had some influences on the tongues of Men.
Melkian, named after the rebellious Melkor or Morgoth, is the origin in the First Age of the many tongues used by the Orcs and other evil beings. (This tongue is unrelated to the Black Speech of Sauron.)
Tolkien later revised this internal history. The Elves were said by Tolkien to have been able of inventing (constructing) their own language (see Primitive Quendian). Tolkien never wrote an 'updated' version of the Lhammas that would be coherent with this later internal history of the Elvish languages. The essay as it stands in The Lost Road can be thus seen as an interpolated manuscript, badly translated by Men in the Fourth Age or even later: "For many thousands of years have passed since the fall of Gondolin." (The Lhammas, p. 180). No autograph manuscripts of the Lhammas of Pengolodh were left; the three manuscripts we possess come from the original manuscript through an unknown number of intermediate copies. Only the final chapter of the work of Pengolodh, called Ósanwe-kenta, comes from a much better manuscript and is much less interpolated. It was written as a typescript of eight pages, probably in 1960, and was first published in Vinyar Tengwar (39) in 1998.