|"The dark world has been untouched, unvisited, and unseen by all civilization—mortals and immortals alike—for countless eons. It is a realm of darkness, suffering, and confusion. There are things there that live but do not know it, for chaos has blinded them for ages, forcing them to feed off of pain like a second oxygen."|
|- Austraeoh ch. 123|
The Dark Side of the World refers to the side of Urohringr that was chosen by the Alicorns to not receive the light of the sun or moon. Thus, the world is divided into a "light (Harmonic)" and "dark (Chaotic)" side. What geography exists there is not known. The dark side is the concave side of the circle, a viewer in 6u would see the horizons rise 7.5 degrees above the celestial equator.
The dragon Endrax traveled to the dark side "over thirty millenia ago", according to Luna
Princess Celestia expands: "Chaos spawns chaos, and many beasts are known to roam the lengths of the Dark World. Discord himself came from a realm deep within the shadowed side of the earth. Without sunlight or moonlight, the surfaces of the realm are exposed ceaselessly to the essence of chaos. The dark world is a land of forsaken things, and most things that dwell there and dare to be cognizant are devoid of peace."
Chrysalis mentions several features of the dark side: Tchern's hive, Sarosian and Night Shard armies, the Sarcophagus of Ages (possibly the same as the Midnight Armory), and a "bastion" belonging to Endrax.