Hungary lost of her land & of her population. I'm assuming this would be the reason why it's very hard to find genealogy records This is just so disturbing to those whose Hungarian bloodlines are now severely compromised. Such a wrongdoing!
Hungary, a reluctant player in WWI, paid a price no other modern nation had ever been subjected to. The Treaty of Versailles (Trianon) divided much Hungary's territory between Czechoslovakia, Austria, Yugoslavia and Romania.