well, acording to the game canonical storyline, the great Kung Lao lived and died 500 years ago, and so MK C would happen around this time.
But, since the movies and series tell that the MK tournament takes place every generation, that makes MK C to happen around the 19th century.
And if you pay atention to the clothing of the characters in EarthRealm, you'll probably associate that look to something around 200 years ago, and not 500. i mean, it was all just too sophisticated to fit in the 15/16 th centuries.

In the opening, it says "...centuries ago..", but since the series are not canonical, and that "every generation"-thing is always screwing even more the storyline in the movies and series, i don't really know when it took place.