The first episode is in year 2001 but when transported back to the past in the state of Jiu, it would before Shih Huang Ti became the first self proclaimed Emperor of China, and 3 years before he was proclaimed as such. During this time, it would be known as the time of the Warring States, which lasted from 475-221Bc, thereafter Ying Zhing became Shih Huang Ti and established Qin Dynasty in 221BC and the kingdom fell in 207BC.

During this period, there were 7 states fighting for supremacy over the land, which were Chai, Cho, Yin, Chun, Hon, Jiu and Ngai. In this series, Louis is in Jiu, tyring to get to Chun, his original destination, as Ying Zhing was supposedly the hostage prince from Chun, who will later destroy all 6 other states and unite them under Qin Dynasty. This series focusses primarily on Chun (Ying Zhing, Siu Lung), Jiu (Siu Sin, Madam Ngai) and Ngai (Sung Ling Gwan, Lung Yeung Gwan). Many were famous real life characters, which you can read more about them in characters, but many main characters in this series, such as the women and the lead character are fictional. This story is from a book, which TVB has adapted into a TV series which you will see in the form of this series.

I have tried searching for more info on this chaotic period of time but failed miserably. I took the info below from SPCNET Discussion Forum thanks to the ever resourceful Jennifer.

"Basically this period began with the downfall of the Zhou dynasty (which were divided into the Western Zhou that came after Shang Dynasty fell in 1100BC, Eastern Zhou in 770BC, Spring and Autumn Period, which lasted from 770BC-476 BC and now, we are in the middle of the Warring States, the focus of this series). Without an Emperor to control them, the leaders of the various areas under the control of the Jau ended up calling themselves kings (essentially warlords) and started to create armies of their own. Soon, after fighting amongst themselves for power and land, seven countries or states, formed. They were the Yin and Jiu states to the north, the Chun to the west, the Cho to the south, the Chai to the northeast, the Ngai to the northwest and the Hon to the southwest of the center of China. (Called the Seven Males of the Warring States) The various kings of these seven states continued to struggle with each other for dominance over the rest.

The kingdom that were to be the victorious one would be the Chun. In the beginning, they were not even considered to be a threat to the other six states. They were a barbaric race who weren't even Chinese. The technological capabilites of the people there were not as advanced as the others. Yet they proved themselves capable in terms of military strength. Over the course of years, they slowly conquered the other six states and succeeded in unifying China under one leader, ending the era of the Warring States.

This period wasn't only punctuated by periods of strife and warfare. It also marked the beginnings of various schools of thought, which included Confucius."

To know more, do read More Info.

Below is a complete chart of the events surrounding Qin Dynasty.

314 BC The Qin state scores its first great military exploit (over the northern nomads) after its reorganisation by Shang Yang. 
311 BC Qin annexation of the lands of Ba and Shu in Sichuan in Western China. 
312 BC The upper valley of the Han state occupied; Hanchung, the Han capital captured. 
278-277BC Expansion into Hubei at the expense of the Chu state; General Bai Qi of Qin captures Ying, the capital of Chu. 
c.261 BC Lu Buwei, a merchant from Zhao, befriends Prince Zichu, future king of Qin and father of the First Emperor, while the latter was a hostage in Han Dan, capital of the state of Zhao. 
258 BC Birth of Ying Zheng, future First Emperor of China 
257 BC The Qin army is forced to raise the seige of Handan, capital of the state of Zhao in the Hebei region. 
251 BC Prince Zichu's father (An Guojun or King Xiao Wen) ascends the throne. Through the machinations of Lu Buwei, Prince Zichu was appointed the Crown Prince, with Lu Buwei as his tutor. 
250 BC Prince Zichu ascends the throne as King Zhuang Xiang, and appoints Lu Buwei his Grand Councillor. 
249 BC The petty realm of Eastern Zhou in the Henan region is annexed, marking the end of the Zhou Dynasty. 
246 BC Death of King Zhuang Xiang. Ying Zheng ascends the throne of Qin at 13 years of age. Lu Pu Wei appointed as regent and Li Si appointed a senior scribe. 
Commencement of work on Ying Zheng's tomb at Mount Li. 
238-7 BC The abortive Lao Ai rebellion. Lu Buwei, implicated in this matter, was exiled to faraway Shu. 
Li Si appointed as Justice Minister. 
236 BC Lu Buwei commits suicide. 
233 BC Death of Han Feizi, a leading Legalist philosopher. Death rumoured to have been instigated by fellow student and jealous rival, Li Si.
230 BC Conquest of the state of Han. 
228 BC The state of Zhao is annexed. 
227 BC First assassination attempt on King Ying Zheng by Jin Ke, of the state of Yan.
225 BC Conquest of the state of Wei. 
223 BC Annexation of the Chu state. 
222 BC The state of Yan is conquered. 
221 BC The last feudal state, Qi, is finally annexed by Qin. Ying Zheng assumes the title of Qin Shi Huang Di (or, First Emperor) and promulgates the following policies: 
Abolition of feudalism and the centralisation of power in the form of a non-hereditary bureaucracy loyal to himself. 
Empire divided into 36 commanderies, which were sub-divided into prefectures and counties. 
The standardisation of written language, currency, weights and measures, and legal code. 
Confiscation of weapons, which were melted down to form bells and giant statues, as a deterrence to resistance. 
219 BC Qin Shi Huang's first tour of inspection of the empire. Li Si appointed Grand Councillor. 
First expedition sent in search of the mythical island of Peng Lai and the Elixir of Immortality. 
Second assassination attempt on the First Emperor by Gao Jianli with a lead-filled lute. 
218 BC Third assassination attempt on Qin Shi Huang by Zhang Liang, future strategist to Liu Bang, founder of the Han Dynasty. 
215 BC Second expedition sent in search of the mythical island of Peng Lai and the Elixir of Immortality. 
214 BC Completion of the Great Wall, under General Meng Tian. 
213 BC Burning of the Books. 
An expeditionary force of 100,000 men under General Meng Tian was dispatched against the Xiongnu barbarians in the Ordos region. 
212 BC 460 scholars buried alive on Qin Shi Huang's order. The First Emperor's eldest son, Prince Fu Su, is banished to the Great Wall for appealing clemency for the scholars. Construction of Afang Palace started. 
210 BC Death of the First Emperor while on an inspection tour. Zhao Gao and Li Si send false decrees ordering the deaths of Prince Fu Su and General Meng Tian. Hu Hai ascends the throne as Qin Er Shi Huang Di (or, the Second Emperor). 
209 BC First peasant rebellion in Chinese history. 
208 BC Chief eunuch Zhao Gao double-crosses Li Si and causes the execution of the latter to gain power. 
207 BC Massacre of 200,000 Qin prisoners-of-war by order of Xiang Yu, the leading rebel leader. 
The Second Emperor is forced to commit suicide by Zhao Gao. King Zi Ying (nephew of the Second Emperor) ascends the throne and orders the death of Zhao Gao. 
206 BC Zi Ying surrenders to the rebels, only to be executed by Xiang Yu. The Qin Dynasty comes to an end after 15 years. 
Start of the Chu-Han rivalry between Xiang Yu and Liu Bang. 
202 BC After many setbacks, Liu Bang defeats Xiang Yu and establishes the Han Dynasty.