Question: Which year did Qin Shi Huang unify China?
About the article "Great Wall of China", section "Early walls".

Candidate passages:
  September 10 – Qin Shi Huang, the first emperor of China (b.
260 BC)  Fusu, first son and heir apparent of Qin Shi Huang  Meng Tian, general of the Qin Dynasty of China  
  Qin Shi Huang orders his generals to capture present-day Guangdong and Guangxi.
By place. 
In 247 , the 13-year-old Ying Zheng became king of Qin after the sudden death of King Zhuangxiang.
However, Ying Zheng did not wield state power fully in his hands until 238 , after eliminating his political rivals Lü Buwei and Lao Ai.
Ying formulated a plan for conquering the other six states and unifying China with help from Li Si and Wei Liao.
In 230 , Qin attacked Han, the weakest of the Seven Warring States, and succeeded in conquering Han within a year.
Since 236 , Qin had been launching several assaults on Zhao, which had been devastated by its calamitous defeat at the Battle of Changping three decades ago.
Although Qin faced strong resistance from the Zhao forces, led by general Li Mu, it still managed to defeat the Zhao army by using a ploy to sow discord between King Qian of Zhao and Li Mu, causing King Qian to order Li Mu's execution and replace Li with the less competent Zhao Cong.
Zhao eventually fell to Qin in 228  after the capital city of Handan was taken.
However, a Zhao noble managed to escape with remnant forces and proclaim himself king in Dai.
Dai fell to Qin six years later.
After the fall of Zhao, Qin turned its attention towards Yan.
Crown Prince Dan of Yan sent Jing Ke to assassinate Ying Zheng but the assassination attempt failed and Qin used that as an excuse to attack Yan.
Yan lost to Qin at a battle on the eastern bank of the Yi River in 226  and King Xi of Yan fled with remnant forces to Liaodong.
Qin attacked Yan again in 222  and annexed Yan completely.
In 225 , the Qin army led by Wang Ben invaded Wei and besieged Wei's capital city of Daliang for three months.
Wang directed the waters from the Yellow River and the Hong Canal to flood Daliang and King Jia of Wei surrendered and Wei was conquered.
In 224 , Qin prepared for an attack on Chu, its most powerful rival among the six states.
During a discussion between Ying Zheng and his subjects, the veteran general Wang Jian claimed that the invasion force needed to be at least 600,000 strong, but the younger general Li Xin thought that 200,000 men would be sufficient.
Ying Zheng put Li Xin in command of the Qin army to attack Chu.
The Chu defenders, led by Xiang Yan, took Li Xin's army by surprise and defeated the Qin invaders.
The defeat was deemed as the greatest setback for Qin in its wars to unify China.
Ying Zheng put Wang Jian in command of the 600,000 strong army as he had requested and ordered Wang to lead another attack on Chu.
Wang scored a major victory against the Chu forces in 224  and Xiang Yan was killed in action.
The following year, Qin pushed on and captured Chu's capital city of Shouchun, bringing an end to Chu's existence.
In 222 , the Qin army advanced southward and annexed the Wuyue region (covering present-day Zhejiang and Jiangsu provinces).
By 221 , Qi was the only rival state left.
Qin advanced into the heartland of Qi via a southern detour, avoiding direct confrontation with the Qi forces on Qi's western border and arrived at Qi's capital city of Linzi swiftly.
The Qi forces were taken by surprise and surrendered without putting up resistance.
Following the fall of Qi in 221 , China was unified under the rule of Qin.
Ying Zheng declared himself "Qin Shi Huang" (meaning "First Emperor of Qin") and founded the Qin Dynasty, becoming the first sovereign ruler of a united China. 
During his stay in Qin, Li Si became a guest of Prime Minister Lu Buwei and got the chance to talk to the ruler of Qin, King Zheng who would later become the first emperor of a unified China, Qin Shi Huang.
Li Si expressed that the Qin state was extremely powerful, but uniting China was still impossible if all of the other six states united to fight against Qin.
Qin Shi Huang was impressed by Li Si's view of how to unify China.
Having adopted Li Si's proposal, the ruler of Qin spent generously to lure intellectuals to the state of Qin and sent out assassins to kill important scholars in other states.
In 237 BC a clique at the Qin court urged King Zheng to expel all foreigners from the state to prevent espionage.
As a native of Chu, Li Si would be a target of the policy so he memorialized the king explaining the many benefits of foreigners to Qin including "the sultry girls of Zhao".
The king relented and, impressed with Li Si's rhetoric, promoted him.
The same year, Li Si is reported to have urged King Zheng to annex the neighbouring State of Han to order to intimidate the other five remaining states.
Li Si also write an article of Making Stop Exile Non-Qin Kingdom Government Officer in 234 BC, it is Jianzhuke Shu.
Han Fei, a member of the aristocracy from the State of Han, was asked by the Han king to go to Qin and resolve the situation through diplomacy.
Li Si, who envied Han Fei's intellect, persuaded the Qin king that he could neither send Han Fei back (as his superior ability would be a threat to Qin) nor employ him (as his loyalty would not be to Qin).
As a result, Han Fei was imprisoned, and in 233 BC convinced by Li Si to commit suicide by taking poison.
The State of Han was later conquered in 230 BC.
After Qin Shi Huang became emperor Li Si persuaded him to suppress intellectual dissent.
Li Si believed that books regarding things such as medicine, agriculture and prophecy could be ignored but political books were dangerous in public hands.
It was hard to make progress and change the country with the opposition of so many "" scholars.
As a result only the state should keep political books, and only the state run schools should be allowed to educate political scholars.
Li Si himself penned the edict ordering the destruction of historical records and literature in 213 BC, including key Confucian texts, which he thought detrimental to the welfare of the state.
It is commonly thought that 460 Confucian scholars were buried alive, from the well-known historical event "Burning Books and Burying Confucianists" (焚书坑儒), however this was a mistranslation in later historical texts.
In reality the 460 people who were buried alive by the emperor Qin Shi Huang were mainly priests and shamans who were scamming the emperor of resources and wealth claiming to be looking for medicine that grants eternal life or apotheosis. 
The He Shi Bi () is a piece of jade which plays an important part in many historical stories in Ancient China.
Found in the State of Chu by a man named Bian He, it was first made into a jade disc, then into the Imperial Seal of China by Qin Shi Huang.