For those who were asking: the Columi were one of the galaxy's ancient technologically-advanced civilisations, pre-dating the Rakata and the Infinite Empire. They're mentioned in one of the datacron Codex entries. Actually the Columi still exist, but their civilisation isn't what it once was. Neither are the Columi themselves....

Our pronunciation guide for "Columi" is something like "KOH-lu-me".

Just as a note: the "true dark sons of Tython" is not intended to refer to Master Rajivari's followers and apprentices.