Ever Night Time Period

I am an American so there is probably something I missed, but in the beginning of the show it said "During the     "Tianqi Era" which I looked up and it said that was 1621 -1627.  However during the show the Princess is of the Tang Empire (618 - 907) also she marries a Prince of the Golden Horde (1242 - 1502).  

If anybody smarter than me can answer this I would be very appreciative!