While reading over the wikipedia page for Holocaust victims , I noticed that Buddhists were listed as one of the non-Jewish groups persecuted by the Nazis. However, subsequent google searches on "Buddhists in the Holocaust/Buddhist Persecution in the Holocaust/etc." yielded almost no relevant source material.
So I'm left wondering: why were Buddhists targeted by the Nazis? The iconic Nazi Swastika itself is a symbol often seen in Buddhist culture, so I'm not understanding why they would be viewed as threatening or degenerative to the Aryan race, as so often was the Nazi justification for murdering innocent people.
There was not concentrated persecution campaign against Buddhists in Germany, not in the least because of the comparatively small number of Buddhists in Germany. There however were Buddhist victims albeit comparatively few.
These included people who under Nazi laws were considered Jewish but had converted to Buddhism at some point in their life. Virtually the only sources for this come from the Deutsche Buddhistische Union (German Union of Buddhists), which was founded in 1955 but traces its roots back to the beginning of the 20th century and the first prominent German Buddhists in Germany that appeared sometime around the German unification. Notably, their publications from the 1980s about one of their oldest members, Helmut Klar who converted to Buddhism in the early 1930s and served as a doctor during the war mentions in passing that people considered Jewish under Nazi laws faced persecution by the Nazis but it does not expand on that any further, the same way it mentions the Gestapo trying to requisition a library full of Buddhist writing though there too it is not expanded on why they would do that. Possible reason could include the SS leadership's own relation with Eastern esotericism and mysticism or possibly just suspicion of something foreign. Klar himself served in the war without facing any discrimination for embracing his Buddhism and even entering a Buddhist name into his marriage certificate in 1942 apparently.
Other Buddhist victims come from the German Asian community. The history of the Asian community in Nazi Germany is not that well researched to be honest. The only significant Asian community in Germany I have come across is the Chinese. In 1935 there were about 1.500 to 1.800 Chinese people in Germany, most of them living in Hamburg and Berlin having been sailors and settling down there. The Chinese in Germany were faced with several discriminatory measure, especially since many had ties to leftism and some had even served with the Republicans in Spain.
In 1938, the Reich Security Main Office (RSHA) under Reinhard Heydrich instituted the Zentralstelle für Chinese, a bureau with the specific task of preventing Chinese immigration to Germany and controlling those Chinese who lived there. In Berlin, the members of this RSHA bureau interned all the Chinese living there in Arbeitserziehungslager Langer Morgen. Arbeitserziehungslager were not Concentration Camps in that they were not run by the WVHA but instead by the local Gestapo. These camps were smaller but the living conditions there were not significantly less brutal than in the Concentration Camps.
In Hamburg, in May 1944 the Gestapo raided the part of town to which the Chinese living there had been forcibly confined in 1942. The so-called "Chinesenaktion" resulted in an additionally 130 Chinese being sent to Langer Morgen, where some of them such as Chan Ho Bau and Liang Wong were murdered.
And finally, the policy towards Soviet POWs meant that Soviet citizens from the Asian republics, which included Buddhists were murdered by the Nazis. It is an often forgotten example of racially motivated murder by the Nazi but they generally murdered East Asian and specifically Mongol Soviet soldiers. Together with Jewish POWs and Bolshevik Commissars, they belonged to the group of Soviet POWs who were singled out specifically to be killed by the Einsatzgruppen. The Mongols as the embodied of the "Asiatic Horde" in Nazi racial delusions were seen as especially dangerous too. Where they weren't killed immediately, they often found themselves deported to the larger Concentration Camps such as Auschwitz to be killed there. The exact number is not known but it is important to include them in the racial victims of the Nazi regime.
Martin Baumann: Helmut Klar. Zeitzeuge zur Geschichte des Buddhismus in Deutschland. 1995.
Lars Amenda: „Chinesenaktion“: Zur Rassenpolitik und Verfolgung im nationalsozialistischen Hamburg. In: Zeitschrift des Vereins für Hamburgische Geschichte. Band 91, 2005, S. 103–132.
Lars Amenda: Fremde, Hafen, Stadt. Chinesische Migration und ihre Wahrnehmung in Hamburg 1897–1972 (= Forum Zeitgeschichte. Bd. 17). Dölling und Galitz, München u. a. 2006.
Herbert Diercks: Der Hamburger Hafen im Nationalsozialismus. Wirtschaft, Zwangsarbeit und Widerstand; herausgegeben von der KZ-Gedenkstätte Neuengamme, Hamburg 2008.
Benton, Gregor (2007), "Germany", Chinese Migrants and Internationalism, Routledge, S. 30–37.
Gütinger, Erich (1998), "A Sketch of the Chinese Community in Germany: Past and Present", in The Chinese in Europe von Benton, Gregor; Pieke, Frank N., Macmillan, S.199–210.
For Nazi racial policy and the Mongols: Richard Breitman: Hitler and Genghis Khan. In: Journal of Contemporary History, Vol. 25, No. 2/3 (May - Jun., 1990), pp. 337-351.