In Mesopotamian mythology, Irkalla (Akkadian, also Ir-Kalla, Irkalia), Kur (Sumerian) or Ersetu (Akkadian) is the underworld from which there is no return. It was also called earth of no return, Kurnugia in Sumerian and Erset la tari in Akkadian. Kur is ruled by the goddess Ereshkigal and her consort, the death god Nergal.
Irkalla was originally another name for Ereshkigal, who ruled the underworld alone until Nergal was sent to the underworld and seduced Ereshkigal (in Babylonian mythology). Both the deity and the location were called Irkalla, much like how Hades in Greek mythology is the name both of the underworld and of the god who ruled it.
The Sumerian netherworld was a place for the bodies of the dead to exist after death. One passed through the seven gates on their journey through the portal to the netherworld leaving articles of clothing and adornment at each gate, not necessarily by choice as there was a guardian at each gate to extract a toll for one's passage and to keep one from going the wrong way. The living spirits of the dead are only spoken of in connection with this netherworld when someone has been placed here before they are dead or wrongly killed and can be saved. The bodies of the dead decompose in this afterlife, as they would in the world above.
As the subterranean destination for all who die, Irkalla is similar to Sheol of the Hebrew Bible or Hades of classic Greek mythology. It is different from more hopeful versions of the afterlife, such as those envisioned by the contemporaneous Egyptians and the later in Platonic philosophy, Judaism, and Christianity. However, Irkalla also differs from the Greek Tartarus and the Christian perspective of hell. Irkalla had no punishment or reward, being seen as a more dreary version of life above, with Erishkigal being seen as both warden and guardian of the dead rather than a sinister ruler like Satan or death gods of other religions.
The underworld had various names, some of which were used for the earth and the surface of the earth as well. Sumerian names are: a.rá, arali, bùr, ganzer, idim, ki, kir5, kiši, kukku (darkness), kur, kur.gi, kunugi / kurnugia (earth of no return), lam / lamma, lamḫu, uraš2, urugal / erigal (grave / great city) and ZÉ.
Akkadian names are: ammatu, arali / arallû, bīt ddumuzi (house of Dumuzi), danninu, erṣetu, erṣetu la târi (earth of no return), ganzer / kanisurra, ḫaštu, irkalla, kiūru, kukkû (darkness), kurnugû (earth of no return), lammu, mātu šaplītu and qaqqaru.
- Encyclopedia of Ancient Deities By Charles Russell Coulter, Patricia Turner