Evolution of Kinship Network and the Rise and Fall of a Dynasty: A Case of the Tang Dynasty

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1 Evolution of Kinship Network and the Rise and Fall of a Dynasty: A Case of the Tang Dynasty Feiyan Liu, Jianbo Gao Institute of Complexity Science and Big Data Technology, Guangxi University March 21, / 13

2 Outline Motivations Data Conclusions 2 / 13

3 Motivations Motivations Ancient China is consisted of a string of dynasties, from Qin (B.C B.C. 207) to Qing (A.D A.D. 1912). The rise and fall of these dynasties seemed to have been repeating again and again: a dynasty appeared to get people s support in the beginning; then became prosperous; in the middle, turmoils emerged; in the end, it lost people s trust and perished. Meanwhile, the rise and fall of a dynasty has a profound influence on people s lives. While most ordinary people were powerless in this process, a few, such as those noble families, had been flourishing throughout this process through various associations, such as marriage. Question: How did social networks evolve with the rise and fall of a dynasty? We take the Tang Dynasty as an example. 3 / 13

4 Data Data China Biographical Database (CBDB, Originated from the work of Robert M. Hartwell of Harvard University, and now is a joint project of Harvard University, Institute of History and Philology of Academia Sinica, Peking University. A freely accessible relational database with biographical information about 360,000 individuals as of March 2017, primarily from the 7th through 19th centuries. The offline version of CBDB is as: 4 / 13

5 Data Data We focus on the individuals of the Tang Dynasty (A.D.617- A.D. 907) : Firstly, we divide the Tang Dynasty into four periods: the Early Tang (A.D.617- A.D. 712), the Splendid Tang (A.D.713- A.D. 762), the Mid-Tang (A.D.763- A.D. 827), and the Late Tang (A.D.828- A.D. 907). Secondly, a list of individuals belonging to each period has been obtained according to their Index Year (the sixtieth year of age ). The length of lists are 8476, 7103, 10260, 10733, respectively. Then, we query the associations among the individuals in each list. It s found that kinship takes the absolute proportion. CBDB being a biographical database,the kinship information there has to be the most detailed. Therefore, we focus on the kinship networks of the Tang Dynasty. 5 / 13

6 Kinship Network during the Early Tang (by Gephi): 6 / 13

7 Kinship Network during the Splendid Tang: 7 / 13

8 Kinship Network during the Mid-Tang: 8 / 13

9 Kinship Network during the Late Tang: 9 / 13

10 For each period of the Tang Dynasty, the kinship network contains two separated parts : a single interconnected central network, and a outer ring The central network is always dominated by the kinship among almost the same group of noble families, such as Tsui of BoLing, Wei of JingZhao, Pei of HeDong, Lee of LongXi (the imperial family in Tang). The outer ring is mainly consisted of those kinship networks not connected with noble families. The relative size of the central network to the whole networks is increasing with time: about 45% in the Early Tang and the Splendid Tang, and about 60% in the Mid-Tang and the Late Tang. In the later periods, the kinship network between noble families became larger; meanwhile, more ordinary families would be absorbed into the central network through marriage. 10 / 13

11 The distribution of the degrees of kinship networks: P(Degree d) Whole Newwork Central Network Outer Ring α w = 2.28 α c = 2.07 α o = (a) Early Tang (Degree) P(Degree d) Whole Newwork Central Network Outer Ring α w = 2.25 α c = 2.02 α o = (b) Splendid Tang (Degree) P(Degree d) Whole Newwork Central Network Outer Ring α w = 2 α c = 1.9 α o = (c) Mid Tang (Degree) P(Degree d) Whole Newwork Central Network Outer Ring α w = 1.86 α c = 1.75 α o = (d) Late Tang (Degree) 11 / 13

12 Considering the distributions of the degrees for the whole network, the central network, and the outer ring network, they follow Power-law distributions. P [Degree d] d α, d For the central network, α is decreasing with time. Note that for the last two periods, α < 2, which means that the variance is infinite. The later the period, the larger the proportion of nodes with extremely large degrees (hubs) is. The increasing number of those hubs could be readily related with the rise of many powerful groups (local authorities) after the An-Shi Rebellion. For the outer ring, α is also decreasing with time, meaning the emergence of kinship networks of relatively big size. 12 / 13

13 Conclusions Conclusions Limitations This is a hasty study since we have just got to know CBDB a few weeks ago. Dividing the Tang Dynasty into four periods might be too rough to gain insights into the evolution of the kinship network. Future Work Take into account geographical information of individuals already captured by CBDB to better the analysis on the kinship networks. Detect communities for the central network for each period; meanwhile, examine how other promising parameters of kinship networks vary with time. More importantly, investigate whether the properties about the kinship networks in the Tang are shared by other dynasties, such Song, Ming, Qing / 13