Forum:Attaining Chunin rank

I have always pondered over the process of gaining the Chunin rank. In the present, Genin have to enter the Chunin Exam to gain it. But the Chunin Exam was said to be a substitute for wars between countries. So before the Chunin ´Exam´ started, did the Genin only need to show themselves worthy in some oother way to gain the new rank?

Guess
Maybe they just needed to perform an act of unusual strength, loyalty, or something like that. Just my guess...