Around 3,400 BCE, in the river valleys between the Tigris and Euphrates, a civilization appeared so suddenly that it still puzzles historians. The Sumerians did not slowly grow out of simpler societies in the region. They arrived, seemingly complete, with writing, mathematics, astronomy, law codes, farming science, metalworking, and a view of the cosmos of stunning complexity. Their literature, pressed into clay tablets in cuneiform, describes in real detail the doings of beings they called the Anunnaki: 'those who from heaven to earth came.' The tablets say these beings arrived from a distant heavenly body they called Nibiru, built cities, mined for gold, and, in the account kept in the Atrahasis Epic, created human beings as a workforce by mixing divine blood with clay.
The main Anunnaki figures in the Sumerian texts are Enki, the god of wisdom, water, and creation, and his half-brother Enlil, the god of wind and command. Their father Anu rules from above. Their conflicts, over humanity, over who rules Earth, over the fate of the flood survivor Utnapishtim, line up closely with stories from other ancient cultures, from the Hebrew Elohim to the Egyptian Neteru to the Hindu Devas. What stands out about the Sumerian texts is how specific they are. These are not tales of vague forces. They describe beings with names, family trees, political fights, feelings, and physical needs. Enki drinks beer. Enlil flies into a rage. Inanna gets jealous. Whatever these beings were, the Sumerians wrote about them like people who had met them.
The scholar who pushed hardest to read the Sumerian texts as literal accounts of alien contact was Zecharia Sitchin, whose 1976 book The 12th Planet kicked off a twelve-volume series called The Earth Chronicles. Sitchin, who taught himself to read cuneiform, argued that 'Nibiru' was a real planet on a long looping orbit, that the Anunnaki were a spacefaring civilization that visited Earth about 450,000 years ago, that they genetically engineered Homo sapiens by mixing their DNA with Homo erectus, and that the gold mining in the tablets was literal, since the Anunnaki needed gold to keep their planet's atmosphere alive. His books have sold millions of copies. They have also been picked apart in detail by mainstream Assyriologists.
The academic case against Sitchin is serious and worth taking seriously. Mainstream cuneiform scholars, including Michael Heiser, himself trained in ancient Near Eastern languages and texts, argue that Sitchin made the same translation mistakes over and over, that 'Nibiru' in Sumerian astronomy texts means Jupiter or Mercury depending on the passage (never a 12th planet), that the Anunnaki are consistently described as gods of the underworld rather than space travelers, and that Sitchin cherry-picked passages that fit his theory while ignoring the ones that did not. Heiser's critique is detailed and grounded in the language itself. It does not settle the deeper question of why the Sumerians had such a precise view of the cosmos, or where their civilization came from, but it does demand honesty about the limits of Sitchin's specific claims.
Set aside Sitchin's specific readings, and the Sumerian texts still contain material mainstream archaeology has not fully explained. The Eridu Genesis, older than the biblical Genesis by at least a thousand years, describes a world before the Flood full of great cities, long-lived kings, and divine presence. The King List opens with the words: 'After the kingship descended from heaven, the kingship was in Eridu.' The Atrahasis Epic describes a deliberate change made to the human species. The Epic of Gilgamesh describes the hero meeting a flood survivor granted immortality by the gods, a figure whose story comes before and closely mirrors the biblical Noah. None of these matches has a satisfying mainstream explanation. The safest reading is cultural borrowing. The boldest is direct experience.