The historical meaning of the term "Hindu" has evolved with time. Starting with the Persian and Greek references to the land of the Indus in the 1st millennium BCE through the texts of the medieval era, the term Hindu implied a geographic, ethnic or cultural identifier for people living in the Indian subcontinent around or beyond the Sindhu (Indus) river. By the 16th century, the term began to refer to residents of the subcontinent who were not Turkic or Muslims. Hindoo is an archaic spelling variant, whose use today may be considered derogatory.