The concept of a Malay race was originally proposed by the German scientist Johann Friedrich Blumenbach (1752–1840), and classified as a brown race. Malay is a loose term used in the late 19th century and early 20th century to describe the Austronesian peoples / categorize Austronesian speakers into a race. Since Blumenbach, many anthropologists have rejected his theory of five races, citing the enormous complexity of classifying races. The concept of a "Malay race" differs with that of the ethnic Malays centered on Peninsular Malaysia and parts of the Indonesian islands of Sumatra and Borneo.