Origin/Historian/Author: Old Babylonian (ca. 1800 BCE)
Source: Revue d’Assyriologie et d’archéologie orientale, 1884

This Old Babylonian text comes to us on a single tablet with no breaks or damages to the text itself. It was perhaps part of a longer composition dedicated to the goddess Ishtar, however, this conclusion is based on speculation. Titled, The Organization of the Heavens, by Wilfred G. Lambert, it describes the ruling gods Anu, Enlil, and Ea, as they worked in unison to allocate positions or tasks to other deities. Here we see the ruling gods designate the moon god Sin to oversee night, while the sun god Shamash would oversee day. On the surface, this text appears to refer to an astrological order, but perhaps there is a more logical explanation.

The first line describes the foundation of heaven and the underworld. We understand this foundation to be a reference to the Anu Ziggurat. The gatekeepers, Sin and Shamash, would rotate between 12 hour shifts. Sin during the night, and Shamash during the day. Aside from being gatekeepers, they were also tasked with maintaining order, perhaps acting as the highest authority for visitors to the Ziggurat, aka heaven.

Full Text Below

At the eternal foundation of heaven and underworld, the sure plans of the gods,
Anu, Enlil, and Ea began to assign lots.
For the two gods, guards of heaven and underworld, who open the gates of Anu,
For Sîn and Šamaš night and day respectively were created.
Their work was assigned from the base of heaven to the height of heaven,
To muster all the stars of heaven (in a straight line) like a furrow,
To keep the leading gods on a (straight) path like an ox.