Funding for this research was provided by:
University of Chinese Academy of Sciences (2019-Y954026XX2)
the Chengdu Archaeological Institute (201812-187)
Youth Innovation Promotion Association of the Chinese Academy of Sciences (Null)
National Social Science Fund of China (17XKG003)
China Scholarship Council (201904910738)
National Natural Science Foundation of China (41471167)
the youth fund of Humanities and Social Sciences of the Ministry of Education, P. R. China (19C14430008)
Article History
Received: 14 May 2020
Accepted: 28 June 2020
First Online: 9 July 2020
Competing interests
: The authors declare that they have no competing interests.