yes it's bullshit. there was no such thing as "ukraine" in a form of a state. those were territories raided by tatars. without poland they would all be taken into slavery and sold in crimea slave markets. you are ignorant as fuck.  the only castles and fortress that gave any protection and shelter were polish ones. kamieniec podolski, stanislawow, podhorce etc . not a single ukrainian castle there.
Poland