Following the victory against the Ming Empire, the United Provinces of Mornaea faced immediate internal instability characterized by crippling war debt and a persistent Loyalist insurgency in the northern province of Sen-Lin. In late 1792, the provisional government dispatched troops to the Hofung Mountains to crush a diverse rebellion of Loyalists, stranded Ming soldiers, and indigenous warriors. With order restored by the following winter, the political elite convened to establish a permanent legal framework for the new nation. The resulting "Charter," ratified in 1794, represented a delicate compromise between the conservative landed aristocracy and the liberal merchant class, establishing a unique governmental system headed by an elected Emperor to bridge the divide between traditional authority and republican ideals.

On the international stage, the young republic opportunistically entangled itself in European colonial conflicts to secure its financial future. In 1795, Britain offered to forgive Mornaea's debts in exchange for a diversionary invasion of the Dutch "Groot Territory" while the British attacked French Ecab. Although the British expedition in Ecab ended in failure, the Mornaean invasion succeeded; the United Provinces occupied vast swathes of the mainland interior, which the Netherlands, viewing the territory as unprofitable wasteland, made little effort to reclaim. This undeclared war effectively expanded the republic's domain onto the continent, securing a massive frontier for future settlement.

Domestically, the Diet elected the revolutionary hero Zheng Mingxi as the first Emperor in late 1794. Mingxi ushered in an era known as the "Years of Harmony" by appointing a balanced cabinet that included both Unionist merchants and National Republican aristocrats. Under the guidance of his Grand Censor of the Treasury, Zhang Shichang, the government navigated a precarious fiscal landscape, eventually establishing a National Bank in 1801. This institution stabilized the currency and managed credit, allowing the republic to clear its debts to Britain by 1804 and funding extensive infrastructure projects, including a national road network that connected the disparate provinces.

As the nation expanded, the government determined that the island capital of Huangcheng was too geographically isolated to govern the growing mainland territories effectively. In 1805, construction began on a new capital in Sen-Lin province, situated on a bay south of the 45th parallel. Named "Pingcheng," the city was designed with a fusion of London's urban planning and the architectural style of the Chinese Imperial City. To prevent inter-provincial rivalry, the capital was legally designated as the personal property of the Emperor. The court officially relocated to Pingcheng in 1814, symbolizing the republic's maturation and its strategic pivot toward the sea and the east.