Professor Lai obtained his BA and MPhil degrees at CUHK, before completing his PhD degree at the University of Toronto. His research specialisations and interests cover the political and social history of the Qin-Han and Wei-Jin periods, kinship systems and studies on bamboo slips and wooden documents. He is currently the Vice Chairman of the Department of History and the director of the Centre for Chinese History at the CUHK.

Professor Lai first introduced us to the historical materials for studying the Qin and Han periods. He argued that in addition to the literature of that time, excavated archaeological data are also very important, such as funerary objects unearthed from the Qin and Han tombs and the large number of bamboo slip materials that bear official documents. In his lecture, Prof Lai selected the Liye 里耶 Qin bamboo slips and Xuanquan 懸泉 Han bamboo slips as cases to present his study on social conditions during the Qin and Han dynasties.

Prof Lai stated that the term "bianhu qimin" 編戶齊民 was often used during the Han dynasty, especially in local society. "Bianhu" 編戶 refers to an account that was used to register the names and identities of all of the members of a household, using the household as its unit. "Qimin" 齊民 meant common people with equal social status. Accordingly, the combination of bianhu and qimin denoted people with equal social status who were included in the national household registration system. During the Qin and Han dynasties, the government attached great importance to the control of the household registration system. In fact, this system had already appeared in the Zhou dynasty. The household registration system provided the government a basis on which to take charge of the registration of households, levy taxes, recruit labour and organise armies. However, do any existing texts present the household registration system? It is recorded in the The Rites of Zhou (周禮．秋官．司民) that "All people including babies are recorded in the documents" (自生齒以上，皆書於版。). This indicates that at that time, the household registration was recorded in some documents. Nonetheless, we still do not know exactly what those documents look like. During the Qin dynasty, besides household registration, there was a parallel system named "shiwu lianzuo" 什伍連坐. We also know from records included on Qin bamboo slips unearthed in Shuihudi 睡虎地 that the Qin government strongly requested that local officials make accurate records of the population, or otherwise face punishment.

Unfortunately, specific and complete archives of the household registration system have not yet been found. Of course, some objects have been unearthed that are similar to household registration records. Professor Lai introduced us to bamboo and wooden slips for garrison soldiers unearthed in Juyan 居延 district that were named "Xu Zong jian" 徐宗簡. He explained that the records contained the soldiers' familial composition, records of land and other property and updated household information on the family, called Xu Zong 徐宗. In addition, he introduced Han dynasty bamboo slips called "Lizhong Jian" 禮忠簡, which may reflect the nature of the property tax levied by Emperor Wu during the Han dynasty. However, these are simply the recruitment records of garrison soldiers, not actual household registration files. However, Professor Lai contended that the Han bamboo slips named "Huang Bu" 黃簿 unearthed in Huxi Mountain 虎溪山 in Yuanling 沅陵 comprise relatively comprehensive census data. The slips record "Fusuan" 賦算 that are clearly related to corvee and tax. He stated that he believes these records serve as the basis for effective management by local officials.

After introducing our basic knowledge of the household records of the Qin and Han dynasties, Professor Lai began to explain the social conditions during these ancient periods as reflected in the Qin and Han bamboo slips. Liye is located in Liye County 里耶鎮, Longshan County 龍山縣, in the Autonomous Prefecture of Western Hunan Provence 湖南湘西自治州. Situated on the north shore of the You River 酉水, Liye is the core area of the Wuling mountain range 武陵山脈. During the Qin dynasty, this area belonged to the Qianzhong prefecture 黔中郡. In the fifth year of Emperor Gaozu, Liye was transferred to the Wuling prefecture 武陵郡, which is part of Youyang County 酉陽縣. The ancient city of Liye was originally discovered in 1996, with a total unearthed area of ​​5,500 square meters. Qin bamboo slips were unearthed within the 5^thto 16^th layers of the 17 different layers that made up the site. More than 36,000 pieces of bamboo slip have been discovered, containing in total about ten million words of texts. The texts are mainly government documents, covering all facets of social life including the post, armaments, arithmetic, notes and so on. Among these slips, around 51 slips of household registration records were discovered in the moat area, ​​of which 28 slips are complete. It remains a mystery why these census data, which were highly thought of by the government, were buried there.

Similar to the Juyan Han bamboo slips that record household data, the words on the Liye household registration slips are also recorded in columns. There are five columns in total, divided by ink lines. Professor Lai used three categories of household registration slips to illustrate their different form and content. The first category, such as slip K27, includes the couple in the centre column; the second, such as slip K17, includes the head of a household and one of his sons together in the first column; while the third category, such as slips K30/45 and K2/23, includes both the head of the household and his younger brother together in the first column. The word "Jing" (荊) in the Qin slips "Nanyang huren Jing" (南陽戶人荊, Nanyang head of a household jing) means "Chu" (楚). This shows that these residents previously lived in the Chu area. Professor Lai then summed up the basic form of the household registration system: the head of the household comes first, followed by the order of seniority of males, then females in the order of wife, mother and concubines; then sons and daughters are separately recorded in two columns; finally servants are recorded and the role of the head. According to seniority, the records of the children of the household head precede the records of the children of the household head's younger brother. The first two columns essentially comprise adults. The gender order of the form also reflects the male-centred society of the Qin dynasty and that it is the men who are mainly responsible for the taxes. Household records also include the relationships between family members and social organisations such as the "Wu ren wei wu" (五人為伍, the five-man army unit). Usually the name "wuzhang" (伍長five-man unit of an army leader) was written in larger font at the bottom of a slip. This was possibly added after the household head was appointed as "wuzhang". The household records contained in the Liye Qin bamboo slips are the earliest census documents from the Qin dynasty. Their form of documenting was inherited by the Han dynasty. This relationship can also be evidenced in other unearthed files, such as in the documents on suanfu (算賦, poll tax) and corvee.

Professor Lai pointed out that the household registration records may reflect the different family types in the Qin dynasty, such as simple, extended and multiple family households. Because the Qin government implemented the fenyi fa 分異法 (law on division of big families and different governmental regulations) where each man was required to register fu 傅 at the age of seventeen to be recruited into the army at any time, his tax could be doubled if he did not separate from his parents to lead an independent family after he was married. Therefore, at that time, the primary family type was the nuclear family. In addition, more than twenty families documented in the Liye household registration slips were likely to have moved from Nanyang County 南陽郡, although the reason for their migration is unknown. According to these records, we do know that the Qin government allowed the migration of some Qianshou 黔首. In both the Qin and Han dynasties, particular officials were in charge of migration.

Finally, Professor Lai presented his investigation of how the Qiang people were assimilated as registered residents of the Han empire using unearthed "Guiyi qiangren mingji" (歸義羌人名籍, the list of affiliated Qiang people) and Han documents of Yue越 people unearthed in Songbai 松柏 as evidence. Numerous historical events are recorded on the Han bamboo slips unearthed in Xuanquan and Dunhuang 敦煌 including chronologies of the periods of the Han emperors Yuan (元帝) and Cheng (成帝), the activities of envoys from Central Asian nations, the contributions of Central Asian nations and the activities of the Han, Xiongnu 匈奴 and Qiang peoples in Hexi 河西. After some Qiang people surrendered or became affiliated to the Han dynasty, they were placed along the Han border and become members of the shuguo 屬國 people. The historical materials show that they had to register their names with the Han community and the prefecture. However, it is still hard to tell whether these records are equivalent to the household registration names. Professor Lai used many examples to demonstrate that the form of these name records was different from that of the Qin bamboo household registration slips. The name records included identity, race, gender and personal data in the centre and the household registrations included the household members in the centre, in the order of the head of the household and the adults, wife, mother, sons according to seniority, daughters and "Wuzhang". Regardless of this difference, the registration procedure still symbolises that the Qiang people accepted the governance and rule of the Han empire and acquired the same social identity, status and responsibilities as registered Han people. This represents the first step in their assimilation into Han society. That is, they began to fulfil their obligation to register and to share the social responsibilities of the Han people.