Al-Biruni's 11th-century text "Tarikh Al-Hind", and the texts of the Delhi Sultanate period use the term 'Hindu', where it includes all non-Islamic people such as Buddhists, and retains the ambiguity of being "a region or a religion". The 'Hindu' community occurs as the amorphous 'Other' of the Muslim community in the court chronicles, according to Romila Thapar. Wilfred Cantwell Smith notes that 'Hindu' retained its geographical reference initially: 'Indian', 'indigenous, local', virtually 'native'. Slowly, the Indian groups themselves started using the term, differentiating themselves and their "traditional ways" from those of the invaders.