<Dd> 咸 言 意氣 高 Were described with praise and awe . </Dd> <Dd> 黃 塵 足 今 古 But today, the past is no more than yellow dust </Dd> <Dd> 白骨 亂 蓬蒿 White bones jostled amongst the grass . </Dd> <P>--Wang Changling (698--755) </P>

What were the periods of construction for the great wall of china