We have the German logs of exactly how many prisoners died each day in each camp and from what cause from the British spying via the enigma machine. The gas chambers story initially started by the Russians after the war which is why all the so called extermination camps are only on the eastern side which the Russians controlled. It was play book soviet propaganda, and since the the west allied with soviets, they adopted it. The Nuremberg kangaroo court were happy to utilize all the propaganda and torture defendants for confessions. All the gas chamber buildings were created / modified by Russians after the war. All historians admits they are modified reconstructions. Forensic evidence shows there is no trace of zyclone b gas being used in any of the 'gas chamber' buildings... but there is strong traces in actual chambers used to fumigate clothes from lice to stop typhus which was the #1 cause of death. Nobody claims those buildings were used for extermination and those buildings were well constructed with solid German engineering.