Assiah (or ‘Asiyah, also known as Olam Asiyah, עוֹלָם עֲשִׂיָה in Hebrew, literally “the World of Action” and Aishah in Arabic) is the last of the four spiritual worlds of Kabbalah -Atziluth, Beriah, Yetzirah, ‘Asiyah- based on the passage in Isaiah 43:7.

According to the Maseket Aẓilut, it is the region where the Ofanim (Hebrew: אוֹפַנִּים ʿōp̄annīm, “wheels”; singular: אוֹפָן ʿōp̄ān, “Ofan” i.e., a class of celestial beings who along with the Cherubim and Seraphim never sleep, but guard the Throne of God) and where they promote the hearing of prayers, support human endeavors, and fight evil.

‘Asiyah is the lowest of the spiritual worlds containing the Ten Heavens and the entire system of Creation. The light of the Sefirot emanates from these Ten Heavens, which are called the “Ten Sefirot of ‘Asiyah”; and through them spirituality and piety are imparted to the realm of matter – the seat of dark and impure powers.

Representing purely material existence, it is known as the World of Action, the World of Effects or the World of Doing.