The best way to do "The ancient World" quest (the one that requires the Gaman horns) is to multi-task.
(1-3 can be done in any order - but concentrate on one job, before doing the others)
1. go out and collect all the tattered map fragments you need in one trip. This can me good for resist training, as you're killing Priests of Mondain. It can also serve as a means to try to "distract" one of the SP PvP guilds for your allies, if you start hacking down their red healers near a popular PvP area. (the same holds true for others doing it in Fel on normal shards).
2. When you go gaman horn collecting, take a butcher's war cleaver or skinning knife (the latter has to be wielded, not just in pack like the BWC), and harvest normal leather as you collect the horns. Gaman are also good targets for high-end taming gains (and, after all, you don't have to collect the horns on the account or character running the quest). Use or sell the leather to other players.
3. Send a naked stealther into the Labyrinth for the minotaur artifacts. You should be able to get enough for 10 trips in one go. You might even manage to sneak in and steal someone's miasma paragon chest off the ground, if they are just looting them and dropping them (wait until they are too involved in combat to notice a disappearing chest).
4. take 10 maps, 30 artifacts, and 200 horns to Heartwood (or whatever you can get away with that doesn't put you overweight). There, you'll just then be running back and forth doing the quest, as you don't actually have to go to the Labyrinth or Tokuno as part of the quest, despite what the quest infers.