Short answers, pulled from the story.
The Han dynasty was an imperial dynasty of China that ruled from 202 BC to 9 AD and again from 25 to 220 AD. It was established by Liu Bang and is considered a golden age in Chinese history. The majority ethnic group of modern China refer to themselves as the Han people.
Liu Bang founded the Han dynasty after defeating Xiang Yu at the Battle of Gaixia in 202 BC in modern-day Anhui. He took the title of Emperor and is known posthumously as Emperor Gaozu, choosing Chang'an, the modern Xi'an, as his capital.
The Han dynasty was named after the Hanzhong fief, where Xiang Yu had appointed Liu Bang as prince. Hanzhong took its name from its location on the Han River in modern southwest Shaanxi. The character Han was also an ancient name for the Milky Way, or Sky River.
The Han dynasty was split into the Western Han, from 202 BC to 9 AD, and the Eastern Han, from 25 to 220 AD. The interruption came from Wang Mang, who declared the Mandate of Heaven had passed to him and founded the Xin dynasty, which lasted from 9 to 23 AD.
The Han dynasty saw the invention of papermaking, the heavy mouldboard iron plough, the three-legged iron seed drill, and the zoetrope lamp. Cai Lun is credited with inventing the standard papermaking process in 105 AD, and waterwheel-powered devices worked the bellows for iron smelting.
The Han dynasty ended in 220 AD when Cao Pi, son of Cao Cao, had Emperor Xian surrender the throne to him. This followed decades of eunuch power struggles, the Yellow Turban Rebellion of 184 AD, and the division of China into three spheres of influence that became the Three Kingdoms.
The Xiongnu were a nomadic confederation of the eastern Eurasian steppe who defeated the Han at Baideng in 200 BC. The Han first appeased them through marriage alliances and tribute, then Emperor Wu launched campaigns from 133 BC that pushed them north of the Gobi Desert at the Battle of Mobei in 119 BC.