The Great Wall of Qi is the oldest existing Great Wall in China. Construction of the wall started in 441 BC by the state of Qi, to defend itself against attacks from the states of Jin and Yue. Construction ended during the Warring States period and became Qi's defense against enemies states like Jin, Lu, and Chu. The wall stretches from the areas under the administration of the present-day city ofJinan to the present-day city of Qingdao across the territories of the present-day cities of Tai'an, Zibo, Laiwu, Weifang, Linyi, and Rizhao. Its total length has been estimated at about 600 kilometers. Most of the wall is still able to be seen.
Dating
Before the discovery of the Tsinghua bamboo strips, several dates have been put forward as the date for the construction of the Great Wall of Qi. The earliest possible date is during the reign of Lord Huan of Qi as mentioned in the Guanzi's "Qing zhong D" chapter. However, the "Qing zhong" chapters of the Guanzi were in all likelihood composed no earlier than the Warring States period instead of the 7th century BCE work they purport to be, and thus could not be seen as a reliable historical source for the Spring and Autumn period centuries removed. The next date is 555 BC, which comes from the Zuo zhuan describing a Jin invasion of Qi that year which involved a Qi fortification, claimed by the Shui Jing Zhu to be part of the Great Wall of Qi. The Zuo zhuan itself, however, never used the term "great wall" or referred to other fortifications along Qi's southern border, throwing doubts into this identification. The date 441 BC comes from the Xinian collection of the Tsinghua bamboo strips, which were discovered from a Chu tomb in Hebei or Hunan and acquired by the Tsinghua University in 2008. Xinian was determined to be composed in the state of Chu no later than 370 BC, which puts it in good authority for the events it describes in its last four sections covering the period from 450 to 395 BC. Specifically, Xinian writes that Qi built the Great Wall "for the first time" after Zhao Huanzi of Jin allied with the state of Yue to invade Qi. This date accords well with other records of battles happening along the wall in 404 BC, 365 BC, and 350 BC from the Bamboo Annals and inscriptions on the Piaoqiang bronze bells.
