Roble Holy Kingdom

Roble Holy Kingdom (ローブル聖王国) or more commonly referred to as the Holy Kingdom is a human nation located southwest of the Re-Estize Kingdom.

Background
The Holy Kingdom as it is simply called, is marked haphazardly on maps of the New World. Their neighboring area, the Wilderness, is inhabited by numerous demi-human tribes who are constantly warring with one another. The country’s border is protected by a wall, the 10,000 Mile Great Wall, keeping the savage tribes from encroaching. The kingdom's national hero is said to be a Valkyrie Knight, wielding the Sacred Blade.

The Lizard Man Heroes Arc
Ainz explains to Albedo in great details about the geography of the Holy Kingdom and it having a wall used to prevent demi-human tribes from encroaching into their territory.

The Men in the Kingdom Arc
It was around this time that Demiruge had already starting preparations to initiate Operation Gehenna in the Holy Kingdom, however, due to certain circumstances he had to initiate it in the Re-Estize Capital.

The Invaders of the Large Tomb Arc
While comparing the strengths of all the leading swordsmen in the lands, the Holy Kingdom's Valkyrie Knight was mentioned by the workers.

The Ruler of Conspiracy Arc
After the massacre at Katze Plains and the establishment of the Sorcerer Kingdom, Demiurge was assigned a mission within the Holy Kingdom for what purpose is still not clear.

The Craftsman of Dwarf Arc
After Ainz finished his business in the Dwarf Kingdom, Demiurge began to set his plans for the Holy Kingdom into motion.

Military Strength
According to the Web Novel, the kingdom's military conscript their citizens when they reach a certain age.

Trivia

 * In the Web Novel, it is stated that the Holy Kingdom have once maintained connections with the Slane Theocracy, but due to the encroaching warring demi-human tribes, the latter lost contact.
 * Demiurge was sent to the area and collected the skins necessary to produce magic scrolls.
 * While normal human skin can only be used to create scrolls that contain magic in the first rank, The skin from humans in the holy kingdom can create scrolls that can hold up to the third rank.
 * The Great Wall here could be a reference to the Great Wall of China, built to keep out the Huns.