The Wizard War “ended” about three hundred years before the beginning of the game. Nobody’s really certain when it really began. Stories tend to begin when the war finally engulfed the original storyteller’s life. What is understood is that it began – and ended – with the arch-lich Nepharides.
Spellcasters of great power can sustain their lives well beyond a normal human’s allotted time. Some wizards are rumored to have been able to sustain their lives almost as long as that of the elves, who have been known to reach the ripe old age of a thousand years. But some spellcasters are powerful enough to take this one step further, and not just extend their lives, but replace them with an undead existence. The process to do this is rumored to require some pretty horrible acts of torture and murder, so it’s not an option for a wizard with an ounce of humanity.