An ordinary civil servant, dreaming of reviving Huaxia and uniting the world, transmigrates back to the mid-to-late Tang Dynasty, already in decline, and becomes Prince Li Chun. His first task is to find a way to defeat the rival factions. After winning, he ascends the throne and becomes emperor. But the Tang Dynasty is plagued by eunuchs meddling in government, regional warlords ruling independently, and a weak economy. Li Chun tackles these problems one by one, making the country prosperous and powerful.
The protagonist advances in waves. First, he defeats the regimes surrounding East Asia, recovers lost territory, and conquers the entire region. He then spends several years making the country richer and stronger and consolidating his gains. Once the nation has grown powerful, the Tang Dynasty launches several successive waves of large-scale wars of conquest, subduing Europe, Asia, and North Africa. After several more years of consolidation and development, it begins another series of wars to conquer the remaining regions, ultimately uniting the entire world.
The protagonist governs as he conquers, proceeding steadily and cautiously. He divides the peoples of the world into four major groups: Hua, Xiang, Yi, and Man, and governs them through a combination of winning them over, keeping them in check, and administering them according to rank. At last, every people in the world comes under the rule of the Huaxia nation, and he devotes his life to fulfilling his dream.
In the end, the Huaxia people become the world's leading nation, and Huaxia civilization becomes the dominant culture. All Huaxia people enjoy lives of dignity, prosperity, and peace.