The Osmanhs are more commonly know as the Ottomans in the western world, were considered as one of the most well organized fighting force at the verge of the 16th century. The Ottomans originally migrated into Anatolia under the leadership of Osman (ruled 1281-1326) and his ghazis after successfully defeating the Seljuks. They established a state in Western Anatolia during the 13th century that challenged the Byzantines in southeastern Europe. By 1453, the Ottomans under the rule of Mehmed II conquered Constantinople, which became their imperial capital, Istanbul and thus eliminating the Byzantine Empire. And in the 16th century the Ottoman empire infiltrated into Europe up to Vienna. This fighting force also defeated the Persian Safavids and the Egyptian Mamluks. Thus for the next two centuries the Ottomans continued to expand, and by the 18th century they ruled a large empire that included all of southeastern Europe, the Crimea, North Africa, and the Middle East to the borders of Persia. And even though the Ottoman empire was unsuccessful to conquer the western European states they still remained the greatest threat to Europe through the 18th century.