Board Thread:Episode Discussion/@comment-24573226-20170121144613/@comment-26397825-20170121163606

Well it's been ravaging villages for at least 13 years (if we go with Ren being 5 in the flashback), and was strong enough all the hunters (not Huntsmen) in the village couldn't slow it down. I'd say it's probably a couple of decades old by now, and has learnt quite a bit in that time.