Air temple sanctuaries (Earth-1529)

The air temple sanctuaries are massive ancient chambers located in the Southern and Northern Air Temples, originally sealed to be open only through airbending. They were considered important to the Air Nomads duo to the knowledge stored on them about the Avatar and the Avatar's previous incarnations.

History
Monk Gyatso, Mito Uzumaki's mentor, confided in her that one of her descendants were supposed to meet someone special within the air temple sanctuary to guide them during their Avatar journey.

A century later, Mito's grandson, Naruto Uzumaki, visited the Southern Air Temple alongside Team Kakashi. Recalling what Gyatso told Mito, Naruto opened the sanctuary's doors with his Rasengan. There, he came across a long line of statues of the previous Avatars. There, for the first time, he saw his future pet winged lemur, Momo, after watching from a doorway behind them. Sakura Haruno and Sasuke Uchiha ran to catch Momo, while Kakashi Hatake took him to befriend him. The chase led the shinobi to the corpse of Gyatso, and the subsequent rage Naruto felt led him to turn into a primitive version of the Nine-Tails, only to be made to stop by Kakashi.