I think it's still canon for Origins that Snake Mountain was present in Preternia and King Hiss took it for his throne.

We all know that Preternia was established, though not named, by Mattel designers for King Hiss's introduction.
Rattlor, Tung Lashor and ancestors of Kobra Khan were left on Eternia when King Hiss, Sssqueeze, Snake Face, Reptilax and the unnamed Snake Men on this page were hurled into a timeless dimension by the Council of Elders.

I can't figure out the current lore as to whether Lord Gr'Asp, Terroar and all of Axel's Snakes were there.