Many centuries ago, a special Naga child was hatched. She was half snake, half humanoid, like her mother, but she had the most wondrous set of wings. It was widely believed, though never confirmed, that the father was Undine, God of the Sea.
Her mother named her Euryali, and as she grew, it soon became apparent that she had an aptitude for magic far beyond most of her people. Sadly (though this is a story for another time), Euryali was feared by the Naga Queens, and was exiled from her home. She travelled deep into the Mists, into the places even the Naga fear to slither, and there she learned many secrets including the dark powers of necromancy.
When Euryali returned, it was with a host of Undead Naga at her back. A fierce battle raged for many years, and although Euryali was defeated, her body was never found. The Bone Naga however, still persist deep within the swamps, and are just another reason the Naga still refuse to travel into the Heart of the Mists to this very day.