Why Magyarország-ON and not -BAN?
Because it's an exception to the rule.
Hungary must be the European equivalent of Kansas, where I live...
It is a basin, surrounded by a mountain range. The tallest mountain in Hungary is about 2/3 of a mile.
Could this also be 'There are a few.....' ? (Emphasising that there are more than none though not many)
Hungary may not have those, but fortunately there is a place with lots of mountains and valleys where Hungarians live: the Székely lands of Romania.