The "Northern Dynasties" refers to a series of Chinese dynasties that ruled northern China during the period from the late 4th century to the 6th century. This era includes the Northern Wei, Eastern Wei, Western Wei, Northern Qi, and Northern Zhou. These dynasties were characterized by their efforts to unify China after the fragmentation that followed the fall of the Han Dynasty. The Northern Dynasties were notable for their promotion of Buddhism, which flourished during this time. They also saw significant cultural exchanges and developments, including advancements in art and architecture, as well as the establishment of the Sui Dynasty, which eventually unified China in 589 AD.