"In the eleventh century the growing internal weakness of the Islamic world was revealed by a series of invasions, the most important of which, that of the Seljuq Turks, created a new military Empire stretching from Central Asia to the Mediterranean. [...] In time of trouble and danger, the new Turkish masters brought a measure of strength and order - but at a cost of higher military expenditure, firmer control of public life, and stricter conformity of thought."
Bernard Lewis
nota: estas invasões tiveram um profundo impacto na Península Ibérica, que estava a atravessar um longo período de tolerância cultural e religiosa, o qual tinha por exemplo possibilitado uma das épocas de ouro do judaísmo.