Southern and Northern dynasties (420-581)

Several Xianbei regimes, including Northern Wei Dynasty (386-534), Eastern Wei Dynasty (534-550), Northern Qi Dynasty (550-577) and Northern Zhou Dynasty (557-581) continued to construct and expand the Great Wall as strategic defensive lines against northern nomadic tribes like the Turkic people and Rouran. Furthermore, a mutual defense wall was built between the eastern and western regimes, such as between the Northern Qi and its neighboring regimes.