Or to say a more accurate statement, there is no evidence of a single such civilization existing. There is also no evidence of a continent sinking into the ocean several thousand years ago.
The "evidence" the Nazis cite for an "Atlantean" civilization makes more sense as being the artifacts of local civilizations. For example, there have been bronze-age civilizations up and down the Andes for several thousand years. The Egyptian pyramids are fascinating artifacts, but were likely built by native Egyptians and/or their slaves (Nubians, Kushites, and Israelites among them) - about 3-5,000 years ago. As for a large continent? The major impetus for the "Atlantis" story in ancient Greece was the tale of the Minoan civilization on Crete, the oldest known Greek state, which was destroyed about 3300 years ago by a volcanic eruption on Santorini (this is about the time of the Israelite's escape from Egypt in the bible, too - several of the "plagues" were likely the result of the effects of a large volcanic eruption).
My statements regarding "Indo-Europeans" have to do with linguistics research from the 19th century and today. It seems at some point around 4 or 5 thousand years ago, a single ancestral tongue to the Indo-European language family was spoken in Central Asia by groups of horse nomads not unlike the modern Turkish residents of this land (this is probably the closest thing to an actual "Atlantis" you're talking about - the linguistic home of most of the "white" peoples of the world). Over several thousand years, these nomads went west and south in groups, these "groups" being the ancestors to modern families of languages within Indo-European. The ancestors of the Celts, Greeks, and Italic peoples were the first to head west, followed by the "Germanic" tribes - Franks, Goths, Angles, Saxons, Norse, etc., with the Slavs, Balts, Bulgars, and Magyars coming behind them; the Turks remaining in place or heading to the southwest to the Caucusus and modern Turkey; the ancestors of the Persians and Indians heading southward.