Boundary Stone of Ritti-Marduk (British Museum, No. 90,858)
The accompanying illustration, which is reproduced from the Boundary Stone of Ritti-Marduk (Brit. Mus., No. 90,858), supplies much information about the symbols of the gods, and of the Signs of the Zodiac in the reign of Nebuchadnezzar I, King of Babylon, about 1120 B.C.
The mutilated text of the Fifth Tablet makes it impossible to gain further details in connection with Marduk’s work in arranging the heavens. We are, however, justified in assuming that the gaps in it contained statements about the grouping of the gods into triads.
In royal historical inscriptions the kings often invoke the gods in threes, though they never call any one three a triad or trinity. It seems as if this arrangement of gods in threes was assumed to be of divine origin.
In the Fourth Tablet of Creation, one triad “Anu-Bel-Ea” is actually mentioned, and in the Fifth Tablet, another is indicated, “Sin-Shamash-Ishtar.”
In these triads Anu represents the sky or heaven, Bel or Enlil the region under the sky and including the earth, Ea the underworld, Sin the Moon, Shamash the Sun, and Ishtar the star Venus.
When the universe was finally constituted several other great gods existed, e.g., Nusku, the Fire-god, Enurta, a solar god, Nergal, the god of war and handicrafts, Nabu, the god of learning, Marduk of Babylon, the great national god of Babylonia, and Ashur, the great national god of Assyria.
E.A. Wallis Budge, et al, & the British Museum, The Babylonian Legends of the Creation & the Fight Between Bel & the Dragon Told by Assyrian Tablets from Nineveh (BCE 668-626), 1901, pp. 11-2.