—Mystery of the Emblem
Thabes is a lost city that appears in the Archanea Series, originating from Fire Emblem: Shadow Dragon and the Blade of Light. Set in the far north reaches of the desert of Mamorthod, the civilization was said to have been powerful and prosperous but ultimately brought to ruin by their own hubris. During the present day of the series, Thabes is primarily known for the treasures buried beneath the desert sands. Noticable landmarks associated with Thabes are the Tower of Thabes and the Thabes Labyrinth.
It is revealed in Fire Emblem Echoes: Shadows of Valentia that Thabes was constructed thanks to the guidance of the Dragon Brethren and the Divine Dragon King Naga. Fearful of humanity's amassed power, the Divine Dragon Duma invaded Thabes and had the city destroyed after three days of battle, causing the survivors to flee from the land.
At some point during Thabes's golden age, the alchemist Forneus attempted to find a way to raise the dead as obedient soldiers and create a perfect being. At first the senate of Thabes collaborated with his experiments by providing Divine Dragon blood, but grew fearful of him after messengers and later soldiers were sent into his workshop and never returned. Ultimately, Forneus's workshop was sealed away in what would be later known as the Thabes Labyrinth.
During the War of Shadows, the Dark Pontifex Gharnef makes the abandoned city into his main seat of operations and uses its lost technology to boost his own magic. After the fall of Altea, Gharnef also imprisons Elice in the Tower of Thabes. Towards the end of the war, Elice's brother, Marth, and the Archanean League are teleported to Thabes by Gotoh in order to defeat Gharnef and reclaim the stolen Falchion.
Thabes is an edit of Thebes, which was a capital city in ancient Egypt and could be attributed to Thabes being in a desert.