What is the attire from RPG's with characters like a bard, knight, warrior, etc inspired from?

I think that, much like steampunk is a combination of old-fashioned technology and Victorian high fashion, RPG fashion is a combination of medieval garb (particularly the armour) and various other parts of history. There are very few RPGs where you can trace the setting and characters to a specific time and place in history. Those that you can are typically built around a theme, like medieval China.