Trayastriṁśa Heaven (忉利天). The second of the six desire heavens.
Heaven of Thirty-three (Skt: Trayastrimsha; Tib: sum-chu tsa-sum): Thirty-three realm
The highest of the god realm abodes in Buddhist cosmology; it is atop Mount Meru and ruled by Indra.
It is on the top of Mount Sumeru, and the first desire heaven is halfway up Mount Sumeru, while all other heavens are up in the sky.
Trayastriṁśa Heaven means Thirty-three Heavens, all ruled by the god-king Śakro-Devānām-Indra, who is commonly called Śakra or Indra.