<human>:  When did the Nazis start to use the term ‘Aryan’?
<bot>: The Nazis started to use the term “Aryan” in the 1930s. It was originally a term used by Indo-European linguists to refer to the language groups they believed to be the earliest to develop into modern European languages. The term “Aryan” was later appropriated by the Nazis to refer to a specific race of people, and it became associated with the notion of “racial purity”.