Let me add one additional complication. Two millennia ago the Chinese used the name Daqin (Great Qin) to refer not just to themselves, but to refer to the Roman Empire.
 
https://depts.washington.edu/silkroad/texts/hhshu/notes11.html
 
from the notes to the translation by John E. Hill of
 
"A Translation of the Chronicle on the ‘Western Regions’ from the Hou Hanshu.
Based on a report by General Ban Yong to Emperor An (107-125 CE) near the end of his reign, with a few later additions.
Compiled by Fan Ye (398-446 CE)."
https://depts.washington.edu/silkroad/texts/hhshu/houhanshutextonly.html
 
Enjoy the confusion!
 
Dan Lusthaus