Gridania

Gridania's history begins with Gelmorra, the subterranean city-state founded by Humans and Elves around the year 740 of the Sixth Era. In 1076, a Human sorcerer named Jorin Lightheart created a way to use magic to commune with the elementals of the forests above. Successful in gaining their permission to dwell within the forest, he led the people of Gelmorra from their caverns to found the city-state of Gridania.
The people of Gridania lead largely peaceful lives, but the Ixal who inhabited the forest before being evicted by the elementals seek to reclaim the forest as their own. In 1468, they also had to defend their territories from Ala Mhigo in a conflict known as the Autumn War. However, the Ala Mhigans were swiftly routed when Ishgard, Limsa Lominsa, and Ul'dah lent their aid to Gridania, driving them from the forest by 1469.
The current leader of Gridania, Lunafreya Nox Fleuret created the Order of the Twin Adder in 1572 to combat the Sixth Calamity, the elementals were severely weakened, making the Black Shroud a less threatening place to outsiders, but leaving the city-state vulnerable to incursions.
Like Gelmorra before it, the majority of Gridanians are Elven and Human. However a rift formed between the Elves when they were asked to leave Gelmorra. Those who chose to dwell in the forests became the Wildwood Elves(Wood Elf, Eladrin), and those who tried to remain underground became the Duskwright Elves(Dark Elves, Drow), with no love lost between the two. The Blackshroud is also home to some Tiefling clans, who often face discrimination like the Duskwrights.

Reasons to be here:

Commerce/trade: Gridania is home to many exports, wooden goods and materials, leather and meat products from the abundant flora in the area, fruits and vegetables that can only be grown in the Black Shroud, to name a few.
Gelmorran Artifacts: While there are few undiscovered Gelmorran ruins left, ruins of the underground cities still lie relatively intact and unplundered. Those properly equipped to deal with the conditions and the danger can find great rewards exploring the ruins.
Salvage: At the height of the Garlean invasion of Aldenard, the empire constructed castrum at the edges of the Black Shroud. The castrum along the border of Gyr Abania and the Black Shroud are still heavily manned and make up the giant barrier between the imperial territory and Gridania, called Baelsar's Wall. At the other ends however, lie many abandoned castrum, some still containing supplies or useful materials.
Exploration: Whether commissioned by the Cartographers Guild or the Order of the Twin Adders, there is money to be made in mapping the vast expanses of the Black Shroud.
Baelsar's Wall: It is not uncommon for refugees fleeing imperial rule to be seen passing through Baelsar's Wall, either with assistance, guile, or ingenuity.