The Himalayan Wars were a series of conflicts between the Akashic Brotherhood and the Euthanatos lasting nearly six hundred years. The war resulted in the unification of the Euthanatos as a tradition and the formation of the Ahl-i-Batin.
Akashics moving into northern India first came into contact with various Thanatoic cults around 950 BCE such as the Dacoits, Handura and Idran. For a time, they worked together, sharing insights about luck, fate, and the transitory nature of the world. However, for the nascent Euthanatos, the Akashics seemed disturbingly removed from the world and the Wheel of Fate, while the Akashics became disturbed by the willingness of Thanatoic cults to kill in the name of karma.
These conflicts came to a head in 900 BCE, when the two groups were nominally allied in handling an outbreak of plague in Bhutan. When an Akashic named Smoke Tiger witnessed a Dacoit named Ranjit killing the sick, they two came to blows, and Ranjit was killed. Whether Ranjit was simply euthanizing patients too far gone for healing, or whether it was part of a larger plot by the cult at the time remains unclear. Despite attempts to smooth over the incident with diplomacy, within a year the Akashic General Chan Ng had begun rounding up the various cults for extermination. The cults, in response, joined forces to resist Akashic offensives, and in the process came to understand more about their common philosophical perspectives.
By 850 BCE it became clear that the early victories of the Akashics over the disorganized cults were temporary. The dead on both sides reincarnated, returning as newly-Awakened children and youths still bearing old grudges. As the cycles of violence continued, many members of both traditions developed psychological problems from several lifetimes' worth of violence, and many were tempted towards infernalism. Some of these damaged people united into corrupted cults called naraki. Around 535 BCE an attempt was made at negotiating a peace, but the lack of unity among the cults made it impossible to maintain.
In 514 BCE, a party of Akashics crossed paths with an ecstatic cult called the Darwushim in Afghanistan after a battle with the Handura. This encounter, called the Night of Fana, was the genesis of the Ahl-i-Batin.
Over a century of the war's history is shrouded in mystery, thanks to power counter-intelligence magic that still prevents scrying on events. After 384 BC the cults had organized into two sects, the Natatapas and the Consanguinity of Eternal Joy, and in 354 BCE these groups were able to finally drive the last Akashics from South Asia. They then joined with one another for from the Chakravanti.
While the sense of the Himalayan War(s) as a long, ugly conflict fought across multiple lifetimes has always been present, the exact dates of the war have been given differently in several different sources. These differences do not exactly correspond to version. The Book of Shadows: The Mage Players Guide (1993) give the dates of 900-600 BCE. The Second Edition Euthanatos Tradition Book (1997), in the space of a few sections, gives the dates 900-300 BCE, says the war lasted "three hundred years," puts the Night of Fana in the 165th year of the war (putting the start in 679 BCE) and describes the final unification of the Chakravanti as beginning after 235 years of war. The Revised Edition core rulebook, from 2000, restates the "three hundred years" number, while the dates above are taken from the Revised Edition Tradition Book: Euthanatos (2002).