Alcadizaar the Conqueror was arguably the greatest leader of Nehekhara, and in a sense, the savior of the entire world. He is second only to the great King Settra in his conquests but his name has fallen from history, much as the rest of Nehekharan history. His combat with Nagash saved the world from domination by the fear of the coming of the Undead, and allowed the world to develop naturally. He was the last living King of Nehekhara. After him, the rulers of Nehekhara became Tomb Kings in earnest.
Alcadizaar reigned in the period of about -1200 by the Imperial Calendar (The coming of Sigmar being 0). His reign was highly successful as he reunited Nehekhara under an iron grip. The kings of Zandri, Numas, Mahrak, Lybaras and Rasetra all bowed their heads to him and offered the greatest of tributes. He was a wise ruler and the region experienced great prosperity and joy. Then Nagash came. In a series of titanic battles, Alcadizaar pushed Nagash back to his realm. Nagash had underestimated this great general, but he would not do so again. Cursed Lahmia was conquered, sacked and its people enslaved, but from then on plague racked the country. The River Vitae ran red with blood and poison (being renamed the River Mortis) and every living thing suffered, if not died. The Liche Priests were the only unaffected people as they were beyond death. This is when the land became desolate, the dead outnumbering the living. Alcadizaar sat upon his throne and wept, for he could not fight this enemy with swords and arrows.
Then, for a second time, Nagash came forth and easily swept aside the ragged and thinned defenders. Alcadizaar was carried off in chains to the palace of Nagash. Nagash then unleashed the most terrifying spell in history, his powers reaching all corners of the kingdom. Every living thing was stripped of its life and its soul, and the dead were forced to rise to serve the ancient necromancer. A single person was still alive, however, Alcadizaar was languishing in Nagash's cell, safe from the deadly power he was unleashing. He somehow escaped from the prison with the aid of "a group of hunched, heavily cloaked figures" (presumably Skaven) who gifted him with a sword of pure Warpstone (The "Fellblade") and ran to the throne room where Nagash was recovering from his spell casting. Even though Nagash was weak, he was still a powerful sorcerer and warrior. After a titanic battle, Alcadizaar slew the necromancer, ending the threat of the long dead Kings of Nehekhara being bound in eternal servitude.
Alcadizaar wandered his destroyed Kingdom in despair until his weariness, wounds and the mutating and poisonous effects of the Warpstone sword he carried overcame him and he died at the River Mortis. His body was swept downstream and into the Great Ocean and eventually washed up on the shores of the Badlands where it was found by a young human shaman called Kadon.