Gods of Mhach and Skalla

[ObsidianFire]

Who says it's hiding in it's closet? It's right out there in the open. Ala Mhigo is a barren land and the thing they are best known for are their mercenaries since that's one of the easier things to do there and get money from. Both refugees from Mach and Ampador fled there, so who knows how long it took them to sort things out. The situation when Nyunkrepf landed there had descended into war so much that he and the people he saved from the flood went back to Sharlayan. It even takes 1100 years since the 6th Astral Era started for the actual city/country of Ala Mhigo to be properly founded since there was so much in-fighting within the country over resources. Oh, and Illsabard has been invading their northern border off and on this entire time as well... honestly, Ala Mhigo is so okay with it's martial history that I'd think they'd be celebrating Rhalgr upending the original Ala Mhigans if that had happened.

[Apoptomon]

Not sure about Skalla, since the part we visit was repurposed by Ala Mhigo. For Mhach, there were questions about statues seen in the Mhach raid series (example); not sure if we got a Koji Komment (a Fernehalwes Affirmation?) though.
As for getting clues from their descendants, Gyr Abania and Belahdia seem pretty different, so I'm not sure what conclusions to draw from there. E.g. Gyr Abania is Mhachi, but has Amdapori influence too, (and in more recent times at least, a focus on Rhalgr). Belahdia on the other hand (and Uldah and Sildih) are big on the scales-motif (but wasn't Qarn also part of that "Azyma sun symbol in Allagan ruins" quandry?), but I can't remember if anything was said about other influences.

[Hinoto-no-Ryuji]

Concerning how much Mhach delved into the void, it's possible that they worshiped Zodiark. Ascian involvement would explain how they got so good at Void magic and how they came to control Ozma. As for Skalla, no clue. They could have worshiped Ralgr but, as you said, we know too little to surmise.

In addition to what Enkidoh said, it's worth noting that Zodiark has nothing to do with the Void - except in the sense that the creation of the Void (ie, the corruption of the 13th Shard) actively hindered the Ascians' plan to resurrect their god. There may or may not have been Ascian interference in their civilization, but an obsession with the Void wouldn't have led to Zodiark worship.

[Yuriane]

As for getting clues from their descendants

While I'm just having a quick look I wanted to put something in here.

It is theorized I believe by Surito Carito that the surviving Mhachi fled to Thanalan and founded Belah'dia.

The White Mages of Amdapor probably fled underground resulting in the Gelmorans, they seem to be good at making subterranean wards (ei their dungeons)

The few surviving Nymians likely took to the seas and eventually returned to Vyllbrand around the same time Limsa Lominsa was founded, long forgetting their history

Gyr Abania was inhabited by both refugees of Mhach and Amdapor, with a little more of the Mhachi I reckon given that the common name for the region is in the Mhachi tongue. But the Amdaporians likely were more involved in the founding of Ala Mhigo as Amdapor was predominately Hyurian if I recall.

[Gilded]

Who says it's hiding in it's closet? It's right out there in the open. Ala Mhigo is a barren land and the thing they are best known for are their mercenaries since that's one of the easier things to do there and get money from. Both refugees from Mach and Ampador fled there, so who knows how long it took them to sort things out. The situation when Nyunkrepf landed there had descended into war so much that he and the people he saved from the flood went back to Sharlayan. It even takes 1100 years since the 6th Astral Era started for the actual city/country of Ala Mhigo to be properly founded since there was so much in-fighting within the country over resources. Oh, and Illsabard has been invading their northern border off and on this entire time as well... honestly, Ala Mhigo is so okay with it's martial history that I'd think they'd be celebrating Rhalgr upending the original Ala Mhigans if that had happened.

To add on this, the religion of Rhalgr values strength. In order to 'destroy', one must be 'strong'. The burning comet mentioned in the Ala Mhigan myths led them not into a fertile land of bounty, but to a harsh land of jagged peaks and dry wastes. An environment like this would only permit the strong to thrive. While the 'people following a comet' story might sound tame for a deity of destruction, it did lead to centuries of tribal warfare and the creation of a culture valuing martial strength.

Now I wonder whether Gyr Abania in the time of the 5th Astral Era was the same dry, dusty mountainous region that it is right now. Scarce resources would mean warfare between its inhabitants, which (again, reaching) may lean towards the worship of warlike deities like Rhalgr or Halone.

I'm also wondering if the Old One boss in Skalla was Skallic or Ala Mhigan. It's reminiscent of those laser pots in Amdapor, though it's kind of a...mammet? It could be a guardian placed there by the Ala Mhigan royals to prevent trespassers from the underwater entrance to get into the royal tombs and treasury (it does curse you to transform to a spriggan, just like how a certain court thaumaturge cursed people to become monsters...). Alternatively, it was a Skallic creation and the reason why the Ala Mhigan influence (cursed ones, mummies, treasures) is restricted to one side of the dungeon -- the Ala Mhigans weren't able to open the Old One's door from their side, and never knew of the underwater entrance.

As another aside, beyond a defensive standpoint, why would anyone build a city in the bottom of a ravine? It struck me as something incredibly difficult, and the Skallic people built that city for centuries...

[Grimr]

I have often wondered about who the mhachi worshiped if they indeed worshiped any deity. Rhalgr seems obvious to me being the deity of destruction. It would seem odd that ala mhigo would choose that same deity when they have more of an influence from monks.

The Old one could be a mhachi guard but we saw a working one in weeping city. The two could not be more different. I almost want to say Skalla used hexing magic but all that could of been because of the one thurmaturge in service to Theodic the mad king.

[Cybylt]

The White Mages of Amdapor probably fled underground resulting in the Gelmorans, they seem to be good at making subterranean wards (ei their dungeons)

I thought Gelmorra was founded by elezen displaced by the hyuran migration that created Amdapor, it existed concurrently with the other cultures rather than being a direct result of the floods. Some amdapori came to them for refuge but they weren't founders.

[Kuroka]

Now I wonder whether Gyr Abania in the time of the 5th Astral Era was the same dry, dusty mountainous region that it is right now. Scarce resources would mean warfare between its inhabitants, which (again, reaching) may lean towards the worship of warlike deities like Rhalgr or Halone.

The BLM quests tell us that Gyr abania actually looks better now then back then when Mhach was still fine.