Why to bribe?

Hello,
I usually play at immortal level but I never used bribing, because ... I don't know what I can gain doing it. Someone may explain?

For example, ideal case:

I can bribe Montezuma to attack Mansa Musa, the cost is low.
What do I gain?

Maybe ... I "gain" that Montezuma won't attack me for some time?
Or maybe I slow down Mansa Musa research?