The Sumerian word kur means mountain. It also means foreign land. And it also means the place the dead go, which they get to by going down. A language in which the underworld and the highlands are the same noun is telling you that "outside the alluvial plain" was a single category — everything beyond the flat irrigated country was other, and the dead were simply the furthest out.
Its other names are more specific. Kur-nu-gi-a and Akkadian erṣet la târi both mean "the land of no return". Irkalla is a name for the place and sometimes for its queen. Ganzir is the entrance and the palace behind it. In Akkadian it is often just erṣetu, the earth.
What it is like down there
The description is remarkably stable across a thousand years and several texts, which is unusual for this material. The scribes reach for the same set phrases every time: "the house from which no one who enters comes out, on the road whose journey has no return"; the house whose residents are deprived of light; where dust is their food and clay their bread; where they are clothed like birds, with wings for garments; where they sit in darkness and see nothing. Dust lies on the door and the bolt.
Social rank persists and is inverted or flattened. The Akkadian description notes that those who wore crowns and ruled the land in former days are down there serving cooked meat, baking bread, and pouring water from waterskins. High priests and exorcists are there too. Everyone is.
There is no judgement. This is the point that most surprises readers coming from Egyptian, Greek or Abrahamic material, and it deserves to be stated flatly: nothing in the Mesopotamian sources sorts the dead by conduct, no ordeal awaits the wicked, no reward awaits the just, and no one is transferred to a better region for having lived well. What determines your condition below is not how you behaved but how many descendants you left.
The one thing that helps
The dead depend on the living to feed them. The kispu was a regular offering — bread, water, sometimes beer — made by a household to its named ancestors, with the eldest son responsible, and it is attested in ordinary family documents as well as in royal ritual. A dead person whose offerings continue is fed. One whose line has ended is not.
Tablet XII of the Gilgamesh material, appended from a Sumerian original, contains the fullest account, in the form of an interrogation: the shade of Enkidu is questioned about what he saw, and answers case by case. The man with one son weeps bitterly at a peg driven into his wall; the man with two sits on two bricks and eats bread; the man with seven sons sits among the junior gods. The man who fell in battle has his parents holding his head and his wife weeping over him. The man whose body was left in the open finds no rest. And the man with no one to make offerings eats scraps and leftovers thrown into the street — the worst outcome in the whole system, and one entirely outside the dead man's control.
Ghosts follow from this. An eṭemmu, a spirit that is not receiving what it needs or that died badly, can afflict the living, and Babylonian medical texts include a standard diagnosis — "the hand of a ghost" — with rituals to send it back.
The route, and the staff
The geography is administrative. Seven gates, each opened in turn by the gatekeeper Neti on the queen's instructions; a river to be crossed with a ferryman whose name in one Assyrian text is Ḫumuṭ-tabal, roughly "hurry up and take me"; Ereshkigal on a throne with the seven Anunnaki judges seated before her; Namtar as vizier. Nothing enters or leaves without the exchange being recorded, which is the rule that traps a goddess and kills a shepherd in the descent.
The one genuine visitor's account is the Underworld Vision of an Assyrian Prince, a first-millennium text in which a man named Kummaya sees the place in a dream: fifteen deities described in composite animal form, one after another, each with the head of a bird or a lion or a goat and human hands, ending with an encounter that leaves him screaming. It is closer to a nightmare than to a doctrine, and it is the only text of its kind.
Why this makes the epic what it is
Everything Gilgamesh does follows from the arrangements above. If the afterlife offered reward, the king's grief would be answerable and his journey unnecessary. Because it offers dust and rank flattened to nothing, the only durable good available is what a person makes while alive — which is why the poem ends with a wall being pointed at rather than with a promise. The contrast with a tradition that weighed the heart and offered a field of reeds to the vindicated is the sharpest single difference between the two great river civilisations, and it is worked through on Egypt and Mesopotamia on death and across the underworlds compared.
Persistent misunderstandings
Was Kur a dragon?
An older strand of scholarship, associated above all with Samuel Noah Kramer, read certain passages as describing Kur as a monster — a dragon in the underworld defeated by Enki or by Ninurta, on the analogy of other combat myths. The reading was always contested and is now largely set aside; the passages are better understood as involving the mountain-land or the netherworld itself, and the demon Ninurta actually fights in Lugal-e is the Asag. If you meet "Kur the dragon" in a book, check its date.
Is there any escape at all?
Only by substitution, and only in myth. The rule that a departure requires a replacement is stated explicitly and enforced on the goddess who tries to break it. Ordinary people are offered nothing comparable — no rescue, no intercession, no ritual for release. The heroes who did come back out did so under conditions the texts are careful to make unrepeatable, which is the subject of the heroes who went down and came back.
If the dead are all miserable, why bother with elaborate burials?
Because burial and offerings determine your condition within the underworld, even though nothing determines whether you go there. A body properly interred, mourned by named survivors, and supplied by a continuing household is in a completely different position from an unburied corpse whose ghost roams. Mesopotamian funerary practice makes perfect sense once you stop expecting it to be about salvation and start reading it as being about maintenance.