Sylba had been with the dryads when many of them had come up the Westlands coast in pretty ships beyond northern Frobozz. But they moved away from the pretty water deeper into the great woods, always deeper and deeper. But when the dryads moved one time, Sylba was too sick. Such is the dryad way, that they left Sylba behind. Only her granddaughter, Tyrillee stayed to care for her. But sometime before the end of the First Age of Magic in 966 GUE, Old Sylba died.

SOURCE(S): Enchanter (the novel)