Hello. You did not inform what is affecting the regions, which makes it impossible for this question to be answered accurately. However, I will try to help you in the best possible way.
A region affected by something is that region that was subjected to a stimulus and offered a response to that stimulus. The affected Maya regions are those that received the stimulus more intensely and this made the responses of the region more intense than the responses of the regions that received a weaker stimulus. An example of this occurs when an earthquake affects some cities more strongly than it affects others.