You need to provide all trips you have done, regardless of whether your passport have been stamped or not. In some cases (myself included) this may be difficult because one may not kept a detailed record as CIC requests. I have travelled a lot throughout Europe by car and train and cannot remember which countries I visited when. I included as many as I remember and did include all the countries I've been to, but in some cases the dates are not accurate. I've explained this in a LOE and it has been accepted. (got PPR a few weeks ago). You should still try to do your best in this cases.
Including all the trips you got a stamp in your passport is the bare minimum you should do, because this is something they can very easily check. If they see a stamp that you did not declare, they may reject your application.
It perhaps unlikely they'll ever find out about your trip to Taiwan, but also there's no harm sending a CSE explaining your trip, and there is no need to send proof. I'd rather be safe than sorry.