The sentence "The exact origin of the word Bangla or Bengal is unknown" is misleading and erroneous .The word "Bengal" is derived from the root Sanskrit word "Banga" or Vanga .
This being the case how can you say that the origin of the word " bengal" is unknown.
I am not under any impression that Vyas named everything. But it is very much clear that the place name "Vanga" existed from the times of Vyasa. -