Despite this, some ethnic prejudices later developed among Arabs due to several reasons: their extensive conquests and slave trade;[44] the influence of Aristotle's idea of certain ethnic groups being slaves by nature, echoed by Muslim philosophers such as Al-Farabi and Avicenna, particularly in regards to Turkic and black peoples;[44] and the influence of ideas from the early mediaeval Geonic academies regarding divisions among mankind between the three sons of Noah, with the Babylonian Talmud stating that "the descendants of Ham are cursed by being black, and [it] depicts Ham as a sinful man and his progeny as degenerates."[48] However, ethnic prejudice among some elite Arabs was not limited to darker-skinned black people, but was also directed towards fairer-skinned "ruddy people" (including Persians, Turks and Europeans), while Arabs referred to themselves as "swarthy people".[49] The concept of an Arab identity itself did not exist until modern times.[50] According to Arnold J. Toynbee: "The extinction of race consciousness as between Muslims is one of the outstanding achievements of Islam and in the contemporary world there is, as it happens, a crying need for the propagation of this Islamic virtue."[51]
The famous 9th century Muslim author Al-Jahiz, an Afro-Arab and the grandson of a Zanj[52][53][54] slave, wrote a book entitled Risalat mufakharat al-Sudan 'ala al-bidan (Treatise on the Superiority of Blacks over Whites), in which he stated that Blacks:
...have conquered the country of the Arabs as far as Mecca and have governed them. We defeated Dhu Nowas (Jewish King of Yemen) and killed all the Himyarite princes, but you, White people, have never conquered our country. Our people, the Zenghs (Negroes) revolted forty times in the Euphrates, driving the inhabitants from their homes and making Oballah a bath of blood.
—Joel Augustus Rogers and John Henrik Clarke, World's Great Men of Color[55]