The year 519/1125 was decisive for the situation of Christian communities in al-Andalus. The Christian communities of al-Andalus, suffered a dramatic decrease in their number through emigration, deportation and conversion. Muslim rulers fluctuate between utilizing Christians pragmatically and scapegoating them. The image of Christians in chronicles and related writings during the Umayyad and Taifa periods has been dealt with in a number of studies. Christians played an important role in the internal struggles among Muslims, as their alliance was sought by the contending parties. Alliances with the Christians were so widespread among contending Muslim parties that their scandalous nature was usually remembered only in the context of propaganda and ideological struggle. Starting at the end of the Almoravid period and continuing under the Almohads, a number of Muslim polemical writings against Christianity were written under the fixed form of letters exchanged between a Christian and Muslim, the former having attacked Islam and invited the Muslim to convert.