The Ottomans had a variety of ways of dealing with non-Muslim foreigners. In theory, Islamic law assumed a constant state of war between Muslim and non-Muslim rulers, but in practice, long-term peace arrangements were possible and even common. In terms of diplomacy, the Ottomans’ instruments and peacemaking procedures were similar to those of the West, the Turks likewise building on established customs and practices from the Byzantine period and beyond. The ahdnames were particularly important for international relations; originally unilateral documents, they evolved into more reciprocal instruments, only to become more unilateral again in the second half of the seventeenth century. In theory, peace with unbelievers should be temporary, but in practice, the duration of treaties concluded by the Ottomans reflected their assessment of the likelihood of hostilities resuming; in the case of countries that did not pose any military threat to the sultan’s domains, peace could even be concluded indefinitely. As long as both sides maintained the friendship between the two parties, there was no need to fear the Turks. The interconnected phenomena of slavery and privateering regularly put a strain on this friendship, as men, women and children on both sides were dragged off and sold as chattel. This loss of life and property sometimes led to international incidents, in which the Ottoman authorities made it clear that the basic Islamic parameters of peace could not be ignored with impunity.