#p <nat>Chinese<o>philo<n>Confucious<b>551 Aug 27<d>479<c>Lu
#e <t>use<n>mechanical clocks<c>China<d>700(25)
#e <t>construction<d>221<e>206<n>Great Wall of China<c>China<info>The Great Wall of China winds some 2,400 km along the edge of the Mongolian plateau from Gansu province in the west to the Yellow Sea in the east. Its width ranges from 4 to 12 m and its height from 6 to 15 m. ¶Shi Huangdi of the @Qin dynasty@@, first to unify the Chinese empire, built the original wall in the 3rd century B.C. by linking the earlier walls of states along the northern frontier to demarcate Chinese territory and to thwart invasion. Gates through the wall, such as the main one at Nankou near Beijing became centers of trade and of contact with the northern nomads. The wall was extended to Yumen in Gansu province during the Han dynasty and was reconstructed during the Northern Wei and Sui dynasties. Its present appearance is a result of repairs and additions by the Ming emperors (1368-1644). Ironically, the Manchu conquerors of the Ming were let through a gate in the wall by a traitor.<ref>Grolier
#e <t>dynasty<d>221<e>206<n>Qin dynasty<c>China<info>The Qin dynasty ruled China from 221 to 206 B.C.
#e <t>dynasty<d>206 B.C.<e>A.D. 220<n>Han dynasty<c>China<info>The Han dynasty ruled China from 206 B.C. to A.D. 220.
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#e <t>use<n>paper<c>China<d>100(25)
#e <t>use<n>seismometer<c>China<d>132<info>The Chinese scientist Chang Heng invented the seismometer.