Unlike the fortifications of the Great Wall built during the Qin Dynasty (221 BCE-206 BCE), portions of the wall built a thousand years later during the Ming Dynasty were more elaborate and stronger. Bricks and stone were used instead of packed earth. Mongol attacks made such precautions necesssary. Sections of this wall closest to the capital of Beijing were especially strong. Today the stretch of the wall near Beijing is almost 400 miles long.