The world they knew before the Flood was cracked up and broken and changed forever by sedimentary mud flows and flooding and volcanic activity. So we have no way of stating with certainty where the Garden of Eden was, or where everyone lived in the first approximately 1500 years of life on the earth before the Flood.
However, in the garden of Eden were 4 rivers, two of which were the Tigris and Euphrates. Possibly when people got off the Ark and saw those two rivers they recognized them as the two rivers from Eden and so named them that but that cannot be proven as fact.
Genesis 2:10-14 ESV
10 A river flowed out of Eden to water the garden, and there it divided and became four rivers.
11 The name of the first is the Pishon. It is the one that flowed around the whole land of Havilah, where there is gold.
12 And the gold of that land is good; bdellium and onyx stone are there.
13 The name of the second river is the Gihon. It is the one that flowed around the whole land of Cush.
14 And the name of the third river is the Tigris, which flows east of Assyria. And the fourth river is the Euphrates.
So the area of the world today that is called "The Cradle of Civilization" is where people generally believe Noah and his family re-started civilization, and perhaps that is approximately where they lived before the Flood as well.
I researched this link and found after much research it to be very wrong. The problem is that Ron Wyatt was looking on Mt. Arrarat. The Ark rested in the MOUNTAINS of Arrarat. Which is alot bigger. There is another team who has found a giant wood structure the size of an aircraft carrier in the mountains of arrarat that seems more promising. I'll try to find the link to their web sight.