Is there evidence that other ancient civilizations believed in a past where the world had one language, as Genesis 11 teaches? Yes, apparently.
11:1 one language. A text from Mesopotamia called the Enmerkar Epic indicates that the people in that culture also believed that the earth had previously had a single language. The tablet reads in part:
“Man had no rival.
In those days the lands of Shubar (and) Hamazi,
Harmony-tongued (?) Sumer,
the great land of the decrees of princeship,
Uri, the land having all that all is appropriate (?),
the land Martu, resting in security,
The whole universe, the people in unison (?),
To Enlil in one tongue…”ESV Archaeology Study Bible, p. 27
Like the better-known parallels to the great flood (e.g. Gilgamesh), it appears that language disaster of Babel was also remembered and passed down in other Ancient Near Eastern traditions. Fascinating.