<P> The Qin dynasty (Chinese: 秦 朝; pinyin: Qín Cháo; Wade--Giles: Ch'in Ch'ao) was the first dynasty of Imperial China, lasting from 221 to 206 BC . Named for its heartland in Qin state (modern Gansu and Shaanxi), the dynasty was founded by Qin Shi Huang, the First Emperor of Qin . The strength of the Qin state was greatly increased by the Legalist reforms of Shang Yang in the fourth century BC, during the Warring States period . In the mid and late third century BC, the Qin state carried out a series of swift conquests, first ending the powerless Zhou dynasty, and eventually conquering the other six of the Seven Warring States . Its 15 years was the shortest major dynasty in Chinese history, consisting of only two emperors, but inaugurated an imperial system that lasted, with interruption and adaptation, until 1912 . </P> <P> The Qin sought to create a state unified by structured political power and a large military supported by a stable economy . The central government moved to undercut aristocrats and landowners to gain direct administrative control over the peasantry, who comprised the overwhelming majority of the population and labour force . This allowed ambitious projects, such as connecting walls along the northern border eventually developed into the Great Wall of China . These projects involved three hundred thousand peasants and convicts . The Qin introduced a range of reforms such as standardized currency, weights, measures, and a uniform system of writing, which aimed to unify the state and promote commerce . Additionally, its military used the most recent weaponry, transportation, and tactics, though the government was heavy - handedly bureaucratic . Han dynasty Confucians portrayed the dynasty as a monolithic tyranny, but this view has been rejected by modern scholars . There was indeed an attempt to restrict criticism and purge traces of old dynasties, but not the alleged burning of books and burying of scholars . Recently excavated Qin texts show a more pragmatic and eclectic approach in contrast with descriptions in traditional texts . Qin administration has been judged to be no harsher than was prevalent at the time . The Qin were not doctrinaire: Confucian and Legalist philosophies coexisted during the reign of the First Emperor . </P> <P> When the first emperor died in 210 BC, two of his advisers placed an heir on the throne in an attempt to influence and control the administration of the dynasty . These advisors squabbled among themselves, resulting in both of their deaths and that of the second Qin emperor . Popular revolt broke out and the weakened empire soon fell to a Chu lieutenant, Liu Bang, who founded the Han dynasty . Despite its short reign, the dynasty greatly influenced the future of China, particularly the Han, and its name is thought to be the origin of the European name for China . </P> <P> In the 9th century BC, Feizi, a supposed descendant of the ancient political advisor Gao Yao, was granted rule over Qin City . The modern city of Tianshui stands where this city once was . During the rule of King Xiao of Zhou, the eighth king of the Zhou dynasty, this area became known as the state of Qin . In 897 BC, under the regency of Gonghe, the area became a dependency allotted for the purpose of raising and breeding horses . One of Feizi's descendants, Duke Zhuang, became favoured by King Ping of Zhou, the thirteenth king in that line . As a reward, Zhuang's son, Duke Xiang, was sent eastward as the leader of a war expedition, during which he formally established the Qin . </P>

What were the main reasons for the fall of qin dynasty