In 221B.C,the fist emperor of the Qin dynasty succeeded in unifying the whole china by conquering the six other rival states.to prevent the Huns from encroachment,he dispatched an army of 300,000 strong headed by a famous general by the name of Meng Tian to oust the Huns beyond the northern arid area.at the same time an imperial edict was issued to link up into one the sections of walls built by the former states of Qin,Zhao and Yan along the northern frontiers,therby forming a long wall,knownas the 10,000 Li long wall.the succeeding dynasties after the Qin kept on the work of maintenance and repairs or having a part reconstructed again and again.the project carried out in the Ming dynasty was the greatest on scale of all others in the olden days of china.
The feudal nobles of the Yuan dynasty(1271-1368)when subjugated by the Ming withdrew to the grassland beyond the northern arid areas,but still they kept on harassing the north borders of the great Ming Empire.apart from that there grew stronger another ethnic tribe called Nuzhen in the northeast.these two forces formed no small a threat to the newly founded Ming dynasty.
therefore,in the very year immediately after the founding of the dynasty,Zhu yuanzhang,the founder took the reconstruction of the great wall as of first importance.he had Xuda,a famous general sent to supervise the rebuilding of the wall,with his ensuing generations to carry on the work the project lasted for about 200 years to finish after the mddle of 15th centurythe great wall we see now is the very one rebuilt in the Ming dynasty on the basise of that left over from the Qing dynasty.
