Meracydia is a currently inaccessible location in Final Fantasy XIV. Lying to the south of the Three Great Continents of Aldenard, Ilsabard, and Othard, Meracydia is one of the main landmasses of Hydaelyn.
Meracydia once flourished with many cultures and races, including a race of tree-like beings that worshiped Sephirot the Fiend, a centaur-like race devout to Zurvan the Demon, a large unified group of differing races and groups under Sophia the Goddess, and lastly the First Brood dragons, Bahamut and Tiamat alongside their children.
During the last years of the Third Astral Era the Allagan Empire with the newly revived Emperor Xande sought to conquer Meracydia. Initial forays by the Allagan military proved successful, but against a united front of the native peoples and dragons they began to stall. This motivated Allagan scientists to produce even stronger chimerical weaponry and Bahamut was slain in a decisive battle.
The tribes of Meracydia summoned their gods, beings known as eikons (presently referred to as primals). There was no recorded summoning prior to the Allagan incursion, and the multiple simultaneous summonings suggest that a third-party, such as the Ascians, were involved. The three most prominent eikons summoned were Sephirot, Sophia, and Zurvan, referred together as the Warring Triad. The eikonic forces pushed the invaders back to the Meracydian coastline. Xande was infuriated and threatened his cadre of mages to kill one a day until a solution was found. The mages in turn researched eikons, and developed summon magic that allowed the Allagans to imprison the Warring Triad and take them to Azys Lla for containment and research until they were slain by the Warrior of Light five millennia later.
The wyrm Tiamat, the mate of Bahamut, attempted to summon him as an eikon. Her grief and rage twisted the shade of Bahamut into a creature of pure violence, again pushing the Allagans back, driving them towards even more technological and magical advancement. Communication with Voidsent was achieved, and Xande held an audience with the Cloud of Darkness. In exchange for infinite fresh corpses for use as Voidsent vessels, Xande convinced them to fight the Meracydians.
As the undead army killed any who opposed them, the newly dead were inhabited by additional Voidsent. Eventually, the shade of Bahamut was overrun and was fitted with Allagan neurolinks, devices that allow for complete control over a dragon. Bahamut was sealed inside of the false moon Dalamud, and propelled into the heavens. At an indeterminate time, Tiamat was also captured and taken to Azys Lla. Despite being able to escape her bonds, she remains imprisoned by her own will out of regret for her summoning. Various other creatures and structures were taken from Meracydia and placed in Azys Lla as objects of research and trophies of conquest.
After the end of the war, Meracydia was rendered a wasteland. Even after the fall of the Allagan Empire some regions still remain uninhabitable, with reclusive populated areas that often attack any who approach.
Due to the constant threat of attack, very little of the region is known. It is known to be just at the south of Eorzea.