Evidence:
* Original text, translation from Sumerian into English: S.N. Kramer in WOLKSTEIN, DIANE / KRAMER SAMUEL NOAH. Inanna, Queen of Heaven and Earth. Her Stories and Hymns from Sumer. New York 1983 (translation from English into German by the author).
[1] Ancient Sumerian sacred texts about the "Divine Wedding" were written down as early as 2300 BC by the daughter of the Akkadian ruler Sargon, Encheduanna, and later written down in cuneiform by the Babylonian ruler Hamurabi around 1750 BC. Their oral tradition, however, is much older and probably originated around 3000 BC or much earlier. Here is a free compilation of texts by Wolkenstein/Kramer (pp. 36 to 49), translated into German by Verena Zingsem, "Der Himmel ist mein, die Erde ist mein... Göttinnen grosser Kulturen im Wandel der Zeiten" (2008), pp. 39 to 51.
[2], Lovers in bed for the union of king and high priestess, in Wolkenstein/Kramer (see above), pp. 43 and 187: Clay slab, Mesopotamia, Isin-Larsa period of Babylon, ca. 2000 - 1600 B.C., fired clay, Basel, Erlenmeyer Collection