the tower of Babel and the one-languages thing was AFTER the flood. Flood: Genesis 6. Babel: Genesis 10.

The people had congregated, in direct opposition to what God had told them to do, which was disperse and re-populate the world. Then they decided to build the tower and got feeling too smart of themselves and worshipped their smartness rather than God so He confused the languages and made them disperse anyway.

more here: [link to ldolphin.org]
Or, of course, in the actual bible Gen. chapters 5-11.

the bible is silent of pre-creation. It begins by saying "in the beginning" so since I am a bible literalist, that is the BEGINNING. If people want to suppose that three-toed Atlanteans were prancing around telepathically saying "Peace" to each other before the Beginning then fine. But the bible does not support the notion of pre-creation civilizations