• Government Type: Monarchic Diarchy
• Symbol: Ouroboros & Five Suns
• Major Races: Elementals, Humans, Lizards
• Major Cities: Ozomatli, Quetzalcamina

Scattered across Splint are pools within sinkholes, known as cenotes. At the right time, and with a little luck, leaping into one of these cenotes will lead one to the vast underground realm of Itlan-Youali. One might expect these caverns to be desolate and dark, like most caves, but Itlan-Youali is anything but. Veins of gold-obsidian carved into intricate shapes deliver light below like several small suns, supporting a lush tropical landscape. The islands of Itlan-Youali float, magically suspended in a thick mist. Some believe that this mist leads to the Kurago, or perhaps the Dreaming. Accounts from those that have descended and survived are discombobulated and confused. The inhabitants of Itlan-Youali are the Tonameyoti Atlaca people, also known as the Tonatiu or, informally, the Tlaca.

Within these dense forests live the mystical alebrijes, as well as multitudes of small dinosaur species. Most impressive, though, are the cities rising above the trees. Itlan-Youali has two capitals, each equal in dignity and power. Despite being aware of the surface world and overall receptive to the occasional visitor from above, Itlan-Youali remains staunchly neutral in world conflicts, refusing to assist Splint in its plight or take a side in any war. Itlan-Youali is based on the Aztec culture.

Gold-Obsidian is a unique form of obsidian found within the ceilings of Itlan-Youali. Gold Obsidian typically forms in veins of glass crystals that travel all the way from the sun in Splint down to the caverns of Itlan-Youali. When exposed to sunlight, the obsidian will shine a golden hue and give off its own light, actually absorbing the sun's energy. When exposed to moonlight, the obsidian will instead shine silvery white, though it cannot actually absorb energy from the moon. This energy can then be tapped into by individuals attuned to specific crystals, though crystals will ambiently let off sun energy if it is not specifically attuned.

Dinosaurs are one of the more common fauna in the caverns. Most species extant in Itlan-Youali are raptors, no bigger than a wolf. A few larger herbivorous species exist as well, mostly armored sorts such as stegosaurus and ankylosaurus. Most have colorful feathers or beautiful armor plates, and a few of these raptor species have been domesticated by the Tonatiu as hunting and sporting animals, for meat, or as pets.

Despite its relatively small size, Itlan-Youali has two capitals: Ozomatli, the Dusk Capital, and Quetzalcamina, the Dawn Capital. As a diarchy, two rulers are chosen: one in each capital city, usually appointed by “divine right” and decided by the priesthoods. Most of these decisions hinge on declarations of past life; each ruler of Itlan-Youali is, supposedly, the reincarnation over many lifetimes of the cities' original rulers. Below the monarchs are the high priests, following a deity known as Tlayahucoatl. Religion guides much of the daily lives of the Tonatiu.

Itlan-Youali policy has always been aggressively isolationist, refusing to take direct involvement in foreign affairs, especially considering the tumultuous conditions above. This is driven mostly by a fear of invasion. The Tonatiu have evaded destruction many times, and are not open to risking this again. Those who disregard this policy and expose Itlan-Youali to outside threats are considered traitors. Some evade this punishment, escaping to the surface. Many of these escapees have formed the Dominion Del Sol.

Also holding immense political sway in Itlan-Youali is the Crystalsmiths’ Guild, responsible for constant maintenance of the gold-obsidian that refracts and delivers light to the underground realms, allowing for the growth of crops. Laws and punishments in Itlan-Youali include:

• Theft, of personal or public property: Fine equal to double the stolen item’s worth
• Tampering with gold-obsidian constructs: Incarceration for 1-5 years
• Assault: Incarceration for 4-7 years and an additional consequence chosen by the victim
• Murder or rape: Incarceration for at least 15 years, or execution depending on degree
• Heretical religious ritual, including open worship of demons, fey entities, or eldritch beings: Exile
• Ownership of another intelligent humanoid being: Execution
• Treason: Execution