I know that they had access to peppers in the Sichuan province, but other places also had access to peppers. If someone mentions Sichuan food, it's almost assumed that it's spicy.
Hunan, Guizhou, and Yunnan food also have spicy food. Nearby, Vietnamese and Thai food have lots of spicy stuff. Even in the North, a lot of places with Muslim-influenced cuisine (Gansu up to the Northeast) have spicy food.
So maybe the question we want to ask is why are those dudes in Guangdong/HK so bland? ;p
Hunter had too many tubas so he turned them into all pepper