[quote=@ActRaiserTheReturned]
Since my population is China, it's definitely whatever the max pop is. . . 
[/quote]This may help:
http://qzil.com/kingdom/
As for the size of your nation by roughly eyeing it I measure it around 35,000 square miles.
Pop density could be anywhere from 70 to 100 men per square mile. Whichever is sympathetic to you.