Another option is to visit museums. Many museums have exhibits related to historical kingdoms. They might have artifacts, documents, or information panels that can give you more insights into the 'kingdom true story'. Additionally, if there are any local historical societies or heritage centers near you, they could be a good source of information as well. They may have archives or knowledgeable members who can point you in the right direction.
You could start by looking in your local library. There are often history books that cover different kingdoms and their true stories. Check the history section, especially those related to the region or time period you think the 'kingdom true story' is about.