Aeon of Strife

The Aeon of Strife was a massive civil war among the protoss, remembered as the bloodiest and most violent civil war ever recorded in galactic history. It lasted for millennia and consumed the homeworld of Aiur, following the departure of the xel'naga and the loss of the species-wide psychic link that had once bound the protoss together. It ended only when the scholar Savassan, who took the name Khas, rediscovered the power of the khaydarin crystals and used them to restore the link, founding the philosophy of the Khala and uniting the protoss into a new society. (StarCraft (manual); StarCraft: The Dark Templar Saga: Firstborn)

Background#

The protoss were a race of humanoid hunters with psionic powers who developed on Aiur. They were discovered by Amon and his follower xel'naga, an ancient and powerful race seeking a species with "purity of form" through which to break the Infinite Cycle. Intrigued by the mental link all protoss shared, the xel'naga manipulated protoss evolution from above, then descended to live among them. The protoss worshipped them as gods, and the Shelak Tribe shared the closest bond with them. (StarCraft (manual); StarCraft II: Legacy of the Void; StarCraft: The Dark Templar Saga: Twilight; StarCraft: The Dark Templar Saga: Firstborn)

The prelude to madness#

Protoss science and psionics advanced quickly, but so did protoss pride, and the tribes drifted apart. The protoss grew suspicious of their xel'naga teachers and cultivated unsubstantiated rumors about them, and the tribes began to lose their connection to the psychic link. Saddened by the lost opportunity, Amon and his xel'naga prepared to leave Aiur. Seeing this as a betrayal, some protoss attacked them, killing many hundreds and even firing on their ships as they departed. The xel'naga took many loyal protoss with them, who would later become the Tal'darim, meaning "the chosen," and would continue to worship them fanatically. (StarCraft (manual); StarCraft: The Dark Templar Saga: Firstborn; StarCraft II: Legacy of the Void)

The xel'naga left behind many artifacts, including an underground city and khaydarin crystals, with the Shelak Tribe safeguarding many of the portable relics. The protoss then fell into a state of madness in which they raged and whimpered, each feeling great self-hatred over their abandonment. The tribes held a love and hate relationship with the xel'naga and great hatred toward one another. (StarCraft: The Dark Templar Saga: Firstborn; StarCraft (manual))

The course of the Strife#

During the Strife, protoss advancement slowed and the tribes waged a massive war against each other. Little is known from this time due to the loss of historical records. The most famous tribe of the period was the Akilae Tribe, renowned to this day as the protoss' finest psionic warriors. The protoss maintained colonies on other worlds, but these too were quickly gripped by the Strife. (StarCraft (manual); StarCraft Compendium Map Archives)

The tribes descended into something resembling madness. In one example, the Mendella Incident, the mainly underground settlement of Mendella was flooded when a rival faction deliberately destroyed a nearby reservoir. The greater landmasses of Aiur were devastated, and many of the planet's non-sapient species were pushed to the edge of extinction. Entire generations of protoss lived, fought, and died without ever knowing of the psychic link their ancestors had possessed, and over time the protoss fell toward a near Stone Age level, becoming frantic legions of merciless killers. As the Strife drew on, many tribes focused their attacks on the Shelak Tribe for its continued veneration of the xel'naga. (StarCraft Compendium Map Archives; StarCraft (manual); Koprulu Sector Systems: Aiur; StarCraft: The Dark Templar Saga: Firstborn)

He Who Brings Order#

In the latter part of the Strife, the Shelak Tribe was frequently attacked, sometimes for its xel'naga artifacts rather than its members. The scholars Savassan and his apprentice Temlaa were more interested in studying the artifacts than in fighting, and announced they would leave the tribe to study them better. As they deciphered copies of the writing on the relics and journeyed across the land, they came upon a trove of khaydarin crystals and were able to form a psychic link with each other. When they returned to show their discovery, the Shelak leader Telkar insisted on using the crystals as a weapon, while Savassan believed that linking minds with other tribes would instead end the war, since the protoss would recognize what they had in common. (StarCraft: The Dark Templar Saga: Firstborn)

Further deciphering led the two scholars to the underground city, where they found evidence of the experiments the xel'naga had conducted on the protoss, including a giant khaydarin crystal that drained protoss of their life energies. Savassan subjected himself to the crystal's draining for a limited time before Temlaa rescued him, and from it he learned much about the xel'naga. He understood that the loss of the species-wide link had caused the self-hatred driving the Strife, and that re-creating the link would let the protoss heal by feeling their collected positive emotions. (StarCraft: The Dark Templar Saga: Firstborn)

With this knowledge Savassan, now known as Khas, meaning "He Who Brings Order," traveled across Aiur teaching the protoss to rejoin the psionic link, a philosophy that became the Khala. He demonstrated the power of the khaydarin crystals at Gyras, ending the feuding there by destroying the battleground. Khas reunited the majority of the protoss into three castes and a new tribe: the Ara Tribe and others who first gathered around him became the Judicator Caste, the next group of tribes became the Templar Caste of warriors, and the majority became the Khalai Caste of workers and artisans. The founding of the Khala ended the civil war and brought on the Second Age for the protoss, during which the Templar Caste fought to protect the new culture from those who rejected it. Secret information about the Aeon of Strife was preserved on the xel'naga shrine world of Zhakul, watched over by a trio of immortal preservers. (StarCraft (manual); StarCraft: The Dark Templar Saga: Firstborn; StarCraft Compendium Map Archives; StarCraft: The Dark Templar Saga: Shadow Hunters; StarCraft II: Wings of Liberty)