But most RenFests seem to cover a period of about 500 years, plus a fair bit of outright fantasy.
At least at my local one, there is a Court playing out a fictional version of a real event early in the reign of Henry VIII, a period right on the cusp which I would call medieval rather than Renaissance. The people involved in that project actually have a good understanding of the history and are trying for some sort of period accuracy. Everyone else...
Why is that period so fascinating? Pretty clothes, and just enough superstitious belief in magic to let you play fantasy stories. Plus the actual history really is cool, even if it's only obliquely referenced.