At its peak in the 1st century BCE, the Western Han controlled approximately 5–6 million km², establishing one of the largest empires in the ancient world. Its territory stretched from the Hexi Corridor and the Western Regions in the west to the Korean Peninsula in the east, from the Gobi Desert and Mongolian steppe in the north to northern Vietnam in the south. This expansion marked the consolidation of imperial authority and the opening of the Silk Road, transforming Han China into a dominant power across East and Central Asia.

Following the restoration of the dynasty in 25 CE, the Eastern Han maintained a vast but slightly reduced territory of approximately 4–5 million km². Its borders extended from the Western Regions and Gansu corridor in the west to the Korean Peninsula in the east, from the northern steppe frontier in the north to southern China and northern Vietnam in the south. While preserving much of the Western Han's geopolitical framework, the Eastern Han faced increasing internal instability and external pressure, marking a transition from imperial consolidation to gradual decline.