one of the greatest atrocities in history occurred during world war 2 when the nazis institudted the sysmatic killing over 6 million jews and other ethnic groups. what is the name of this grroup

It's "The Holocaust"

Explaination:

Pay more attention in school this was a huge disaster!

The answer you are looking for is probably Slavs.

Explanation:

Of the 11 million killed in the holocaust, 5 million were not jewish. The Nazi regime exterminated Gypsies, homosexuals, Blacks, the physically and mentally disabled, political opponents, and Slavic peoples, to name a few. Out of all these, Slavic peoples, or Slavs, most closely match the criteria of the question as an ethnic group.