@NewSun: I think that Aaron would be enough of a philanthropist and environmentalist to want to help protect one of the few cities that still have a natural habitat. Also, there is great significance in these bandits, and it's sort of hinted at in El_Tigre's first post. These bandits aren't just a band of hooligans looking to make good profit. The city of M'alo is vastly wealthy, and one can infer that such a wealthy city in this world can only stay wealthy if it already has an established defense force. Another thing that El_Tigre mentioned was that certain creatures have a good relationship with the humans. M'alo is located in one of the few areas rich in natural resources, so one could also infer that creatures also inhabit this area, and the only way for a city to survive for even sixty years with these creatures is if they have a mutually beneficial relationship. So, regardless of whether M'alo has an established defense force, they are still protected by the native creatures. And if they do in fact have an established defense force, then it would be much harder for random bandits to even attempt to raid M'alo.
So, for Aaron, and for anyone else who might want to know why it would be a worthwhile investment, ask yourself this: Why would a wealthy city mayor of 60 years suddenly ask for outside aid against a group of bandits?
Do these bandits pose a threat that M'alo's defense force and the natural creatures can't handle? If so, how did they suddenly gain this power?
Does the mayor know something about these bandits that he has yet to tell to others?
IC, no one knows about the existence of Zief, but one thing is for certain: Raids have become more and more common in the last 20 years, but this is the first time a wealthy city in a rich environment is asking for help. M'alo ha been attacked before, and has successfully fended off their attackers, but this is the first time they are asking for help so there must be something big going on.