Well before comparing them with the Nazi's please factor in 2600 years of human history, will you. The ancient world was not the modern world, and applying 20th Century ideals to it is not going to result in understanding it better.
Agreed. However, the Spartans were exceptional in their brutality even for the time. Although they never had any intent of conquering the world, they implemented Nazi-type practices in their small corner of it about as completely as any group ever has.
Actually, most all peoples before the development of Christianity and Islam had a master race mentality. They only differed about which group was supposed to be the master. :)