A report on Xiongnu, Han dynasty and Inner Mongolia

The seventh-largest administrative district by area at 453700 km2, Gansu lies between the Tibetan and Loess plateaus and borders Mongolia (Govi-Altai Province), Inner Mongolia and Ningxia to the north, Xinjiang and Qinghai to the west, Sichuan to the south and Shaanxi to the east.

Gansu is abbreviated as "" (Gān) or "" (Lǒng), and was also known as Longxi or Longyou prior to early Western Han dynasty, in reference to the Long Mountain (the modern day Liupan Mountain's southern section) between eastern Gansu and western Shaanxi.

The Yuezhi originally lived in the very western part of Gansu until they were forced to emigrate by the Xiongnu around 177 BCE.

Tang territory, acquired through the military campaigns of its early rulers, rivaled that of the Han dynasty.

In the year 630, Tang armies captured areas of the Ordos Desert, modern-day Inner Mongolia province, and southern Mongolia from the Turks.

While the Turks were settled in the Ordos region (former territory of the Xiongnu), the Tang government took on the military policy of dominating the central steppe.

The Xianbei were a Proto-Mongolic ancient nomadic people that once resided in the eastern Eurasian steppes in what is today Mongolia, Inner Mongolia, and Northeastern China.

They originated from the Donghu people who splintered into the Wuhuan and Xianbei when they were defeated by the Xiongnu at the end of the third century BC. The Xianbei were largely subordinate to larger nomadic powers and the Han dynasty until they gained prominence in 87 AD by killing the Xiongnu chanyu Youliu.

To position the empire against the Xiongnu people from the north, however, he ordered the building of new walls to connect the remaining fortifications along the empire's northern frontier.

Later, the Han, the Northern dynasties and the Sui all repaired, rebuilt, or expanded sections of the Great Wall at great cost to defend themselves against northern invaders.

Dynasties founded by non-Han ethnic groups also built their border walls: the Xianbei-ruled Northern Wei, the Khitan-ruled Liao, Jurchen-led Jin and the Tangut-established Western Xia, who ruled vast territories over Northern China throughout centuries, all constructed defensive walls but those were located much to the north of the other Great Walls as we know it, within China's autonomous region of Inner Mongolia and in modern-day Mongolia itself.

Emperor Wu of Han (156 – 29 March 87BC), formally enshrined as Emperor Wu the Filial, born Liu Che (劉徹) and courtesy name Tong (通), was the seventh emperor of the Han dynasty of ancient China, ruling from 141 to 87 BC. His reign lasted 54 years – a record not broken until the reign of the Kangxi Emperor more than 1,800 years later and remains the record for ethnic Chinese emperors.

Emperor Wu successfully repelled the nomadic Xiongnu from systematically raiding northern China, and dispatched his envoy Zhang Qian into the Western Regions in 139 BC to seek an alliance with the Greater Yuezhi and Kangju, which resulted in further diplomatic missions to Central Asia.

For example, one such official, Yi Zong (义纵), became the governor of the Commandery of Dingxiang (part of modern Hohhot, Inner Mongolia) and executed 200 prisoners, even though they had not committed capital crimes; he then executed their friends who happened to have been visiting.