Except some Middle East countries, in general the best football teams in Asia are basically Japan and Korea... Japan being a bit stronger as a whole (and with higher level domestic leagues), but Korea has slightly better/more famous indivudial players....
Now if you put the usual geopolitics/historical issues in the mix, and superiority/inferiority complex about pretty much EVERYTHING between the 2 (especially by the Koreans), then you got a good recipe for thrashing your neighbor/old ennemy whenever you can