The Pento War was the first major conflict the D'ni faced after moving to the Cavern. Like the Mee-Dis War some 6000 years later, it was fought between the D'ni and the inhabitants of another Age. In both cases, the natives had been spurred into action by a radical faction within the D'ni in a bid to achieve greater power and force their cause on the whole of D'ni.
The precursors to the War began during the reign of King Koreen in 1303 DE, when a member of the Guild of Writers went missing, along with a collection of Books and a sizable amount of Ink. For 17 years, he and the Judges of Yahvo bided their time, Writing illicit Ages in an effort to develop a race of warriors that they could control and drive to war with the D'ni. In 1320 DE, the Judges accessed the Pento Age, and found exactly what they were looking for.
Three years later, in 1323 DE, a group of Pento linked to D'ni and stormed King Koreen's palace, driving his family from the city. As their boat sailed under the Arch of Kings, Koreen's wife gave birth to Ahlsendar, who would be known to history as the Great King. Koreen stayed behind in D'ni to continue to lead the fight against the Pento, and the Judges leading them. He poured money into the Cavern's small military force, but it was too little too late.
In 1352 DE, King Koreen was assassinated by a group of Pento warriors. His family, safe on a private Age, remained there while Ahlsendar, just 29 when the throne fell to him, planned the counter-attack against the Pento. The Judges, convinced of their victory, claimed control of the D'ni government and began to move their troops into other Ages to expand their conquest.
Several weeks later, Ahlsendar's waiting paid off. The Judges, fearing that the leader of the Pento was becoming too powerful to control, turned against him and killed him. Unfortunately, he had not declared a successor, and his two sons began vying for control of the Pento and D'ni. Still Ahlsendar waited, and all the while, rumors of the coming of the Great King as foretold by an ancient prophecy circulated within the city.
Fifteen weeks after his father's death, Ahlsendar returned to D'ni with a small force, reclaiming the palace with relative ease amidst the chaos that had erupted within the Pento's forces. He called a meeting with one of the Pento leaders' sons, Makarr, agreeing to help him defeat his brother in exchange for leaving D'ni completely. Mekarr agreed, on the condition that Ahlsendar write a new Age in which his people could live. The deals were signed, and in 1376 DE, Ahlsendar led a force through to the Pento Age.
There, in the Battle of the Great King, Mekarr's brother Timaue was defeated. After the battle, Mekarr turned over two of the leaders of the Judges to Ahlsendar. Three more were found in the D'ni city. All five were condemned to Prison Ages, and the Books burned, despite the public's demand for their executions.