Midrasch zu Tehillim 106:24

RABBI ELIEZER said: They begat their sons and increased and multiplied like a great reptile, six at each birth, and they were all one people, and one heart, and one language, as it is said, "And the whole earth was of one language and of one speech" (Gen. 11:1). They despised the pleasant land, as it is said, "And it came to pass, as they journeyed in the east" (Gen. 11:2). They went to the land of Shinar, and found there a large stone, very extensive, and the whole plain, and they dwelt there, as it is said, "And they found a plain in the land of Shinar, and they dwelt there" (ibid.).