<P> In 214 BC, Qin Shi Huang secured his boundaries to the north with a fraction (100,000 men) of his large army, and sent the majority (500,000 men) of his army south to conquer the territory of the southern tribes . Prior to the events leading to Qin dominance over China, they had gained possession of much of Sichuan to the southwest . The Qin army was unfamiliar with the jungle terrain, and it was defeated by the southern tribes' guerrilla warfare tactics with over 100,000 men lost . However, in the defeat Qin was successful in building a canal to the south, which they used heavily for supplying and reinforcing their troops during their second attack to the south . Building on these gains, the Qin armies conquered the coastal lands surrounding Guangzhou, and took the provinces of Fuzhou and Guilin . They struck as far south as Hanoi . After these victories in the south, Qin Shi Huang moved over 100,000 prisoners and exiles to colonize the newly conquered area . In terms of extending the boundaries of his empire, the First Emperor was extremely successful in the south . </P> <P> However, while the empire at times was extended to the north, the Qin could rarely hold on to the land for long . The tribes of these locations, collectively called the Hu by the Qin, were free from Chinese rule during the majority of the dynasty . Prohibited from trading with Qin dynasty peasants, the Xiongnu tribe living in the Ordos region in northwest China often raided them instead, prompting the Qin to retaliate . After a military campaign led by General Meng Tian, the region was conquered in 215 BC and agriculture was established; the peasants, however, were discontented and later revolted . The succeeding Han dynasty also expanded into the Ordos due to overpopulation, but depleted their resources in the process . Owen Lattimore said of both dynasties' attempts to conquer the Ordos, "conquest and expansion were illusory . There was no kind of success that did not create its own reaction ." Indeed, this was true of the dynasty's borders in multiple directions; modern Xinjiang, Tibet, Manchuria, Inner Mongolia, and regions to the southeast were foreign to the Qin, and even areas over which they had military control were culturally distinct . </P> <P> Three assassination attempts were made on Qin Shi Huang's life, leading him to become paranoid and obsessed with immortality . He died in 210 BC, while on a trip to the far eastern reaches of his empire in an attempt to procure an elixir of immortality from Taoist magicians, who claimed the elixir was stuck on an island guarded by a sea monster . The chief eunuch, Zhao Gao, and the prime minister, Li Si, hid the news of his death upon their return until they were able to alter his will to place on the throne the dead emperor's most pliable son, Huhai, who took the name of Qin Er Shi . They believed that they would be able to manipulate him to their own ends, and thus effectively control the empire . Qin Er Shi was, indeed, inept and pliable . He executed many ministers and imperial princes, continued massive building projects (one of his most extravagant projects was lacquering the city walls), enlarged the army, increased taxes, and arrested messengers who brought him bad news . As a result, men from all over China revolted, attacking officials, raising armies, and declaring themselves kings of seized territories . </P> <P> During this time, Li Si and Zhao Gao fell out, and Li Si was executed . Zhao Gao decided to force Qin Er Shi to commit suicide due to Qin Er Shi's incompetence . Upon this, Ziying, a nephew of Qin Er Shi, ascended the throne, and immediately executed Zhao Gao . Ziying, seeing that increasing unrest was growing among the people and that many local officials had declared themselves kings, attempted to cling to his throne by declaring himself one king among all the others . He was undermined by his ineptitude, however, and popular revolt broke out in 209 BC . When Chu rebels under the lieutenant Liu Bang attacked, a state in such turmoil could not hold for long . Ziying was defeated near the Wei River in 207 BC and surrendered shortly after; he was executed by the Chu leader Xiang Yu . The Qin capital was destroyed the next year, and this is considered by historians to be the end of the Qin empire . Liu Bang then betrayed and defeated Xiang Yu, declaring himself Emperor Gaozu of the new Han dynasty on 28 February 202 BC . Despite the short duration of the Qin dynasty, it was very influential on the structure of future dynasties . </P>

What led to the decline of the qin dynasty in china