Genesis 11:1-3

Now the whole earth spoke one language and used the same words (vocabulary). And as people journeyed eastward, they found a plain in the land of Shinar and they settled there. [Gen 10:10] They said one to another, “Come, let us make bricks and fire them thoroughly [in a kiln, to harden and strengthen them].” So they used brick for stone [as building material], and they used tar (bitumen, asphalt) for mortar.