Nevertheless, the Ottoman rulers attached great importance to diplomatic relations despite unilateral nature of these relations in order to be a part of world system and power struggle. As opposed to the general view that the Ottomans did not have bilateral relations with the European or Christian states because the Quran orders not establishing relations with infidels and fighting against them (Tuncer, 11), Ottoman rulers were more pragmatic than argued. From the beginning, they established close relations not only with Beyliks (tribes) in Anatolia, but also with the Byzantine Empire. Through inter-tribal or inter-state marriages, they consolidated their power and expanded their territories. Therefore, the Ottoman Empire cannot be regarded as an entity solely ruled by strict Islamic laws, rather it was also influenced by customary laws and local customs. Ottoman Sultans like Mehmed II issued qanunnames (books of law) in accordance with the Turkish state tradition empowered rulers to make laws, so the Ottoman system was not only ruled by religious laws, but also by customary laws. Such a legal system provided flexibility and pragmatism to the policies of the empire. (Yurdusev, 14-15)