I hear "period" mostly from SCA types - which technically means pre-1600; (which would include MOST of the Elizabethean period) but from some Ren-faire types as well - in which case "period" depends on the faire - Usually Tudor or Elizabethean - though could be Stuart/Cavalier or another time period.

then you get the black powder re-enactors, English Civil War re-enactors, American Civil War re-enactors, American Revolution re-enactors all of which have their own "periods"