The office of the sultan changed dramatically over the six centuries of the Ottoman Empire. The first sultan, Osman, was a medieval nomadic chieftain whose domains existed on the edge of the Byzantine Empire. He and his party accumulated wealth through plundering raids. The 10th sultan, Suleyman, was an emperor in every sense of the word and conquered much of Central Europe in the sixteenth century. The final powerful sultan, Abdulhamit II (r. 1876-1909) was an autocratic reformer who covered the empire with railroad lines, telegraph networks, and schools that taught French and calculus alongside Islamic theology.