Speaking of which, the Dragon race was on quite good terms with humans.
Although they secretly competed with each other, the two races had always maintained a good relationship with each other. The Dragon race was a very lazy race. After they were fully matured, they spent most of the time sleeping. Humans, on the other hand, were hardworking. They would regularly send the things which the Dragon race needed to them. In return, the Dragon race would give the humans precious materials which they themselves did not need in exchange.
For example, some dead old dragons would leave behind parts of them which were useful to humans, like their scales. These items were very beneficial to the young offspring of the dragon family.
Therefore, this martial arts assembly between the Dragons and human beings was of great importance—after all, in the universe, only the strongest would be respected. No one wished to disgrace themselves on their own territory, right?