[Why] The decline of the Zhou court drove the lords of the Central Plains into mutual annexation, while peripheral Rong and Di tribes invaded the heartland and threatened the fracture of Huaxia culture. Qi rose first thanks to its coastal salt-and-iron wealth. [What] Duke Huan of Qi raised the banner of "honor the king and expel the barbarians" designed by his minister Guan Zhong, marching north to strike the Mountain Rong and save weak Yan and Wei. He convened nine assemblies of the lords and confirmed his hegemony in the Central Plains. [Who] Duke Huan was the first hegemon of the Spring and Autumn era, magnanimous and unprejudiced in recruiting talent. The worthy minister Guan Zhong carried out comprehensive economic and military reform that supplied Qi with its decisive material foundation. [How] The Nine Assemblies repelled peripheral tribal invasion and preserved the Central Plains core of Huaxia culture. They established the new international geopolitical order of multipolar lordship coalitions in the Spring and Autumn period.
Why
The historic event of Hegemony of Duke Huan of Qi represents a key developmental peak of the Huaxia dynastic system. The dawn of Spring and Autumn multi-polar coalitions. By establishing this moral or administrative benchmark, it continues to shape the structural and philosophical fabric of ancient Chinese statecraft.