"Holocaust deniers, or 'revisionists', as they call themselves, contend that, while mass murders of Jews did occur (although they dispute both the intentionality of such murders as well as the supposed deservedness of these killings), there was no official Nazi policy to murder Jews. Second, and perhaps most prominently, they contend that there were no homicidal gas chambers, particularly at Auschwitz-Birkenau, where mainstream historians believe over 1 million Jews were murdered, primarily in gas chambers. And third, Holocaust deniers contend that the death toll of European Jews during World War II was well below 6 million. Deniers float numbers anywhere between 300,000 and 1.5 million, as a general rule."