Ross School fifth graders studying ancient Sumer perform Zagmuk procession.

Zagmuk is a Mesopotamian festival celebrated around the winter solstice, which literally means "beginning of the year". It celebrates the triumph of Marduk, the patron deity of Babylon, over the forces of chaos, symbolized in later times by Tiamet. In Uruk the festival was associated with the god An, the Sumerian god of the night sky.