Why is The Boy in the Striped Pajamas historical fiction?

The Boy in the Striped Pajamas is historical fiction because it is set in a real historical context, namely the Holocaust during World War II. The novel tells the story of two young boys, one the son of a Nazi commandant and the other a Jewish boy imprisoned in the concentration camp. The novel accurately depicts the brutality and inhumanity of the Holocaust, but it also tells a fictional story about the friendship between the two boys.