For many centuries, there was mass movement of populations from one continent to another and from one culture to another. According to Ibn Hawkal (2001), Al-Andalus was the greatest centre for human trafficking in the Muslim world. It is difficult to precisely quantify the number of trafficked persons in the absence of reliable figures, but most Arab travellers and geographers claim that the slave trade flow was substantial. The markets of Seville, Cordoba, Valencia and Lisbon were hubs for myriad wealthy merchants - Muslims, Christians, Verdun Jews or Radhānites (Ibn Khurdadhbeh, 1889, p. 153). The raiding networks extended over vast areas of land and sea, linking the Sahara to the Red Sea and the Maghreb, Galicia and Portugal to the Canary Islands, Verdun to Narbonne, Dalmatia to Venice and Central Europe to the Baltic Sea.  
Very early on, a diverse society emerged in which the quest for slaves became a major issue (Ibn Hawkal, op. cit.). Sudanese, Berbers, Slavs, Galicians,  
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[^0]:    3 These texts offer valuable insights for a comparative approach to racialized discourse across space and time (Wheeler, 2000).
4 Letter written by the Emir Abū Ya'kāb Yüssuf ibn Tāshfīn to al Nāṣir li dīn Allab Tamīnn ibn Al-Mu'izz ibn Bādis, Arabic text published by Lévi-Provençal in al-Andalus, vol. XV, 1950, I, pp. 114-24.