In the ninth century, as Muslim society grew increasingly diverse, writers began to describe the merits of their various racial or ethnic groups. In his Kitab al- Imta'wa al Mu'anasah (Book of Enjoyment and Good Company) the tenth-century Arabic philosopher and man of letters Abu Hayyan al-Tawhidi commented on this tendency:

It is not in the Persian's nature nor his custom nor his origin to acknowledge the merit of the Arab, and neither is it in the nature of the Arab nor in his habit that he be delighted at the merit of the Persian. And the same applies to the Indian, the Greek, the Turk, the Dailamite, and others, for the consideration of merit and nobility rests upon two things. The first is that by which one people became distinguished from another, at the time of the creation, by...