Prologues are generally frowned upon, from what I understand, but if used correctly, they can be pretty effective. What I am wondering, is if this method of using one actually falls in the concept of "prologue." It begins with an older man setting up the last of three instruments. Then he goes and sits down at the entrance to the cave he's in, and watches a small group of teenagers in the valley below. His actions and thoughts provide the reader with the overall general (very general) setting, history (without a info dump!) and plot of the story, with I hope, a good plot hook at the end that comes as he dies. The teenagers he sees are the MC and supporting MCs of the story, so its also an introduction to them. The entire scene is just over 600 words. What say you? It's WAY too short to be a chapter. It could be an introduction, but the MC, other supporting MCs aren't introduced, nor is anything specific about their life, except that they are all walking together and seem to get along. So, prologue? Introduction? First scene of chapter one?