Northern Yan
After the fall of Later Yan, Han Chinese drove the Xianbei Murong clan northward and established Northern Yan in its place. However, Northern Yan's existence was threatened by the powerful Xianbei Tuoba clan of Northern Wei to the west, compelling Northern Yan to make an alliance with Goguryeo, its neighbor to the east. Hence, Jangsu turned his military ambitions southward toward the Korean peninsula.