One summer, Monk Tang Xu decided to partake in a fast on Whaletail Island that eventually lasted for over ninety-eight days. Despite urgings from his concerned pupils, Tang Xu refused to eat any food and chose instead to gain nourishment from the universe through meditation.
Monk Tang Xu's achievements were highly regarded to the point where stories of his fast were passed down through generations of Air Nomads. His accomplishments survived the Hundred Year War and became part of the curriculum with which Air Acolytes familiarized themselves during training.
In 171 AG, Tenzin lectured a group of new airbenders about Monk Tang Xu's historic fast, but was dismayed by the general lack of interest among the group. Sometime after, Kya referenced the monk in passing when she remarked that she could never memorize all of the different gurus in Air Nomad culture, as there were too many to remember.