General lore on the Mandalorians. This is primarily common knowledge stuff that those part of the culture would know. By extension, characters who have possibly engaged Mandalorians before, or studied their culture may know this information as well. Please use judgement on it all, however, so as not to have access to information your character shouldn’t know.
Likewise, this category lacks much in the way of historical information. If you wish to view stuff relating to Mandalorian history, feel free to check Wookieepedia. And again, use judgement on what your character would and wouldn’t know.