On Oasis (for example) there are portals to the first maps on Part I, II and III ; but is there some trick to get directly to a map like Sandstorm (which has no portal as far as I can see) ?
I'm hunting for boss-parts (Anubis fibres etc) and on some maps - like Sandstorm - Anubis is easier to reach than on The Great Pyramid, where you land when you select 'go to' for that quest.