in the ottoman empire, tax breaks for "the people of the house" encouraged many people to buy certificates of descent or forge genealogies; the phenomenon of "teseyyüd" – falsely claiming noble ancestry – spread across ethnic, class, and religious boundaries. in the 17th century, an ottoman bureaucrat estimated that there were 300,000 impostors. in 18th-century anatolia, nearly all upper-class urban people claimed descent from muhammad.