Return to Chipmy-Popmy for another cutscene. (You may have to talk to him twice again to get the cutscene.)
Now you need to track down one of the Mithran Trackers in Attohwa Chasm. She is actually located in Boneyard Gully, so you could use the Home Point in Attohwa Chasm if you have previously unlocked it.
Attohwa Chasm, even with a map, can be very confusing. Monsters in the central and eastern areas tend to be non-aggressive to level 60+ characters, while monsters on the west side of the map (the side that Tiamat and Xolotl spawn on) will still be aggressive to a level 75 character.
Cross the bridge (this is very important) and follow the path.
At (H-10), there is an intersection. You want to head east, not west. This will take you into the lower-leveled eastern side of the map.
Follow the mountainside north to (I-8). There is a cave to take you back into the mountain/chasm area.
Follow the path (there is another intersection shortly into the area; head south, not north). The path winds in all directions and takes you all over the chasm. There will be a fork in the path, follow either one south.
You will come to another bridge that crosses the chasm. Continue west.
At (G-7), there is another intersection; head north, not east. You will cross three bridges before you get to the end.
Be very careful once you see the tunnel exit, as Antlions come very close to the mountain. Use Sneak and Invisible and follow the mountain north again.
Also beware of the gasponia flowers along the way, as they can cause a very potent poison effect when getting too close.
Antlions detect by sound so it is safe to renew Invisible near one while avoiding the goblins. As most people know you can cast invisible while its still up so as long as the mob does not detect magic (if you're not using ninjutsu).
At (F-6), there is another tunnel entrance. Follow this tunnel, one bridge to the Boneyard Gully zone, in the eastern part of (G-6).
A mysterious character living on Purgonorgo Isle in Bibiki Bay insists that the island belongs to him. Chipmy-Popmy wants you to participate in the next "debate" over ownership, set to take place in the center of the island.
SPOILER WARNING: Click here for additional details about this story line.