Suhalla Gate

Suhalla Gate is the in-game location through which the Suhalla Range in between Suhalla Desert and the eastern region of Gondowan is crossed. It is unique because it is visited both in Golden Sun and Golden Sun: The Lost Age. From the games' perspective, "Suhalla Gate" collectively refers to the gate checkpoint itself and the mountain trail it connects to. The gate checkpoint itself is owned and maintained by Tolbi; its eastern exit leads to Venus Lighthouse. It also has a cave-like path called Gateway Cave that leads to the area of the overworld called Idejima.

Walkthrough (Golden Sun)
Once you exit Suhalla Desert, follow along the linear path through the landscape until you enter an area of the overworld with a brown path leading through its center; you enter Suhalla Gate as a location. After a brief cutscene on top of the stairs, the door beyond contains a healer who provides Sanctum services. (Incidentally, if you come here through Suhalla Desert before having completed the Colosso Finals, the guards will be stationed at the gate not yet wounded, and prevent you from passing because you lack "travel papers".) Exit to the right, and in the next screen, the first cliff slide you see you should slide down so you get to a chest containing a Mint. Climb up the ivy to the right to exit to the next screen.

In the screen where there is a lengthy series of cliff slides, slide down the third cliff slide from the left to fall down to where there is a Mercury Djinni for you to battle and earn. Once you beat it and add the Mercury Djinni Dew to your collection, go right. Next to the ivy that leads back up is a cave entrance, however, and you may go through it to pick up a Psynergy Stone and lead yourself back onto the overworld where a cutscene, during which you have to use the Black Orb, will play out; while this is entirely optional and is not relevant to the gameplay, it provides storyline context for the start of The Lost Age. Regardless, climb back up the ivy and exit right, and the remaining screen linearly leads you out of Suhalla Gate and into the overworld where you can then enter the area in front of Venus Lighthouse a short distance away.

Walkthrough (Golden Sun: The Lost Age)
Playing alone as Jenna, when you exit left out of the outside area of Venus Lighthouse, you will immediately appear at Suhalla Gate's east exit rather than have to go through a short piece of the overworld first. Go up the stairs, and you'll immediately enter a scripted battle with a Ruffian just like outside Venus Lighthouse; the battle is won very easily by casting Jenna's Fume Psynergy. Exit off to the left; when you attempt to cross left without going down the ivy, Kraden will stop you and tell you that the destination is down through the cave below. When you try enter the cave, however, you will enter a scripted battle with three Ruffians at once; it is still manageable by using Fume to pick them off one-by-one. Enter Gateway Cave and be led by the linear path through to its exit; along the way, an easy scripted battle with a Punch Ant transpires, and then you can grab the Psynergy Stone here. Upon exiting back out into the overworld, the game takes over in cutscenes.

Collectibles
Dew: In the third screen, slide down the third cliff slide from the left to land near this Djinni, which you must then battle to acquire.

Mint: In the second screen, slide down the leftmost cliff to land next to the chest containing this.

Story
Suhalla Gate is an extension of Tolbi that came about during Tolbi's rise to power, and is essentially how Tolbi keeps travel to and from Lalivero, a town under Tolbi's imperial control, regulated. To prevent those who are not sent to work on Babi Lighthouse from coming to Lalivero and the nearby Venus Lighthouse, Babi has stationed guards at the gate who were previous victors of Colosso. The guards are ordered to only let through those that have obtained travel papers for whatever reason.

After this year's Colosso in Golden Sun, Saturos' party of Adepts suddenly come through on their way to Venus Lighthouse. The guards attempt to stop them, but Saturos and Menardi render the guards too wounded to move on the ground with their Mars Psynergy attacks, and proceed forward through the gate to the Lighthouse. Sometime later, Babi's chief minister, Iodem, accompanies Isaac's group of similar Adepts on their own journey to Lalivero; Iodem is shocked to see his soldiers downed, and hear from them about the group that passed through earlier, which is the group Isaac is currently pursuing. At the urging of the downed soldiers, Isaac and Iodem continue on to Lalivero.

Later, at the start of Golden Sun: The Lost Age, two of the group that was traveling with Saturos' group, Jenna and Kraden, return to the mountain pass near Suhalla Gate from the direction of Venus Lighthouse, and go toward the peninsula of Idejima, which Suhalla Gate connects to, because of having been ordered to go to Idejima by Saturos. Ruffians under Iodem's authority had previously attempted to fight those of Saturos' band that had come out of Venus Lighthouse, as an order by Iodem because the group was previously found out to have kidnapped Sheba, but they were scared away into Suhalla Gate's pass by Saturos' companion Alex, who wielded extremely powerful Mercury Psynergy and had since went off to Lalivero to hold off Tolbi's soldiers stationed at Lalivero. However, the ruffians regain their confidence when they see it's Jenna herself and the elderly Kraden passing through, and attack her; Jenna, however, uses her own powers as a Mars Adept to render them twitching on the ground in pain. Jenna and Kraden pass through the cave to get to Idejima, where they wait until Alex goes through Suhalla Gate's pass himself to rejoin them.

Then, when the Venus Lighthouse is lit by Saturos, the tower wracks the landscape surrounding it with an earthquake that, among other things, tears a rift through Suhalla Range, separating Idejima from the rest of Suhalla Range and turning the peninsula into its own buoyant island that floats east out into sea. It is unknown what becomes of Suhalla Gate itself.

Trivia
In The Lost Age, if one uses a walk-anywhere code to go beyond the point where Kraden would stop Jenna and direct her down the vines into Gateway Cave, it will be found that the first two screens still exist in the game code and can be passed between normally. When one tries to exit out of Suhalla Gate through its left exit, they will be returned to the left part of the second screen; the same applies when one tries to enter the door in the first screen that originally led to a sanctum healer. While all the cliff slides still work, there are no collectibles or random monster encounters in any of these screens.