Joran's Path

In the Shadow Elves map, Joran's Path connects the Sharaen, Jorfyn, and Jorlinrath caves. This blazes a Grunland - Alfmyr route, skirting the City of the Stars and the Dragon Lake. Sharaen is below the lava lake in gazetteer Orcs of Thar, which underlies South Gnollistan, which underlies the Sun's Anvil. The southeast Sharean bend (eventually) sits below the Oued Ashuma bend in South Gnollistan.

In 792 BC, a famous expedition to the surface - because the first such - got to the Sun's Anvil. To do that, they could not have got through the lava; they must have taken the Gnollistan detour. One possibility is the Marches. But it is the very northeast corner of the map, and I don't think the elves knew of it then. The other possibility is Jorlinrath, closer to home. The northern tip of Jorlinrath, also 'neath the lava, is further below Bir-Razud. The rest of Jorlinrath is under Kol. The Blackstone Hollow citadel looks promising as a memorial and a guard to that journey. Therefore, the Jorlinrath at least was already known as of 792 BC.

One possibility is that the Path was carved out before the Refuge of Stone was found 1104 BC. However the canon agrees that the Refuge was the first major vault of the Under-Elves - more, that the elves were under Malthusian constraints ("hungry": PG, p. 2) throughout the early 1000s BC, so had not yet found New Grunland. Alfmyr is even further from that. The DMG p. 7 implies that the other cities were seeded only after the coronation 1040 BC.

More likely is that Joran's Path started out an intentional bypass. That is: between 1040 and 792 BC.

The lake-district would be the Celebryl clan heartland; Alfmyr is Felestyr. It happens that Felestyr did, in fact, mix it up with Celebryl. The year isn't remembered, but the day is: Others 22, a day for all to dread as ne fasti. The story goes that Felestyr and Celebryl disputed control of parts of the capital. Celebryl owns the capital now so, we can assume, Felestyr lost this opening battle.

Nobody today calls the Celebryl-Felestyr struggle a "Felestyr rebellion". Felestyr never disputed the shamans nor even the King, over the elvish race; they disputed only Celebryl and that over only the City, and that dispute was conceded. The other clans, we may extrapolate, didn't dismiss this argument. They worried if Celebryl should claim a despotism over the depths. Porador, for one, lodged no objection to Joran's bypass to Felestyr territory.

That Joran's Path still exists implies all the elves accept that the City Of The Stars isn't to be the ultimate nexus to elf life down here.

Therefore I would date the initial civil war, to 1050ish BC. Some version of the city had been built; by 1040 BC, all disputes were settled, and Tarasfir was crowned to universal fasti acclaim. ... in the City.

One leftover problem: soul crystals are what put Alfmyr on the map - literally. No soul crystals implies no Alfmyr. So from 1040 BC to 800ish BC, propose that the elves were in schism: Parador had New Grunland, and Felestyr was carving out new tunnels to the southeast. UPDATE 5/19: A summary.

After Alfmyr waxed great, all was made whole - by necessity. And the City of the Stars carved out its own Jorlinrath Road (tunnel) to the Boiling Lake; it opened its own canal to the Dragon Lake (and another to the North Sojourner). Certainly all was agreed by 448 BC when every elf rallied to protect the central city.