Sparsis is a name spoken mainly in hushed whisper by those that know it. Many of the most well travelled adventurers in the Realms do not know of its location; and those that do stay well away. That it lies off in the jungles of the east is certain, but why it is so obviously a place of death is unknown.
Some speak of terrible undead that roam the area at night. Others tell stories of a plague of such virulence that even the plants sickened and died. Very few people seem to know for sure. And they are reluctant to tell.