Buddhism divided existence into the so-called Three Realms and six paths. The lowest was the Hell Path, followed in ascending order by the Hungry Ghost Path, the Animal Realm, humanity, the Asura Path, and the heavenly path.
The heavenly path was populated entirely by devas and comprised twenty-eight heavens across the Three Realms. The Desire Realm contained six heavens. The Heaven of the Four Heavenly Kings lay halfway up Mount Sumeru, with Vaisravana, Virupaksha, Virudhaka, and Dhritarashtra dwelling in the east, west, south, and north respectively.
Next came Trayastrimsha Heaven, at the summit of Mount Sumeru, where Indra resided.
Any sentient being delivered by a Buddha or Bodhisattva could be brought no higher than this heaven. When Shakyamuni delivered his mother, and Ksitigarbha Bodhisattva his, they could only bring them to Trayastrimsha Heaven. To ascend any higher, one had to cultivate personally; no one else could drag or haul one up by force.
The third and fourth levels were Yama Heaven and Tusita Heaven.
Within Tusita Heaven lay the Inner Court of Tusita, where Maitreya Bodhisattva resided, waiting for the Dharma Extinction Age to pass and the age of true Dharma to return so that he could descend and become a Buddha. Thus, he was called the future Buddha; he was not yet a Buddha.
Many Bodhisattvas one birth away from Buddhahood also resided here. Being one birth away meant that they could become Buddhas after one more reincarnation in the human world. In the future, they would descend alongside Maitreya Bodhisattva, helping him spread the Buddhist teachings and deliver all sentient beings.
Those who cherished this aspiration vowed to be reborn here. The most famous was the Tang monk, Master Xuanzang, who ascended to this very Maitreya Pure Land.
Higher still were the Heaven of Enjoying Transformations and the