Bombs and Cannons from the 1200's

I was looking up some other stuff and I ran into this great discussion of early Chinese firearms.  They had guns.

In it I also found this link to an archeology report about the failed Mongol/Chinese invasion of Japan.  They had bombs.

Does this change the debate about why martial arts were developed in China?

Are Chinese martial arts really really old like African dance? or do they date from the time these weapons were invented?

As I said in a post sometime last Summer, if archaeologists would create a data base of the effects of the lifelong study of various types of martial arts on the bones--we would be able to look at bones from every era and every region and answer this question definitively.