In the 15th century, Dominican friar Annius of Viterbo invoked the Curse of Ham to explain the differences between Europeans and Africans in his writings. Annius, who frequently wrote of the "superiority of Christians over the Saracens", claimed that due to the curse imposed upon black people, they would inevitably remain permanently subjugated by Arabs and other Muslims. He wrote that the fact that so many Africans had been enslaved by the heretical Muslims was supposed proof of their inferiority. Through these and other writings, European writers established a hitherto unheard of connection between Ham, Africa and slavery, which laid the ideological groundwork for justifying the transatlantic slave trade.