The Jyhad is the eternal struggle for dominance between the older generations of Vampires, the Methuselahs, including both the lead up to and the aftermath of Gehenna. The most recent active phase was the War of Blood, pitting the Sabbat against the Camarilla and the Black Hand. Although the Sabbat technically lost and was driven underground once more, the destruction and conquest of the Kingdom of Enoch by the Earth Federation under Arthur Clarke, and the death of the last active Antediluvian, Arikel, has shattered the Camarilla and effectively disbanded the Black Hand, leaving the Sabbat bloodied but still operational, and its leader Mordred as the most powerful remaining active Vampire.
The recent re-emergence from torpor of Ennoia, and the return from self-imposed exile of Malkav, may usher in a new phase of the Jyhad. Ennoia is, for the time being, working with Mordred to unify the remnants of the Camarilla with the Sabbat under their joint control, but their alliance is an uneasy one at best, and the return of Malkav is a major threat to Ennoia's leadership of what's left of the Camarilla.