What are the political, economic, and social factors for building The Great Wall Of China?

i would recommend a book by a scotsman named william lindesey called the great wall revisited. lindesey could be the greatest western experts on the subject and it may be worthwhile trying to contact him online. basically the wall is not just a "wall" but also an elevated military highway. any attempt to breach it is immediately signalled by beacons to the nearest garrison who then uses the wall to march to the point of attack. the aim was to prevent incursions into the empire by the barbarian tribes to the north.