There are big changes coming soon to how posts are closed. You may want to read up on the details here.
For the most part this looks to be a huge improvement. However, it does mean that we will probably want to come up with our own set of custom 'off topic' reasons for the History stack. These reasons will then be available to close voters as selections when they are looking to close a post as off-topic.
So now might be a really good time for us as a community to come up with our own list of reasons why a question may be considered off-topic on this stack. If you have an off-topic reason you'd like to nominate, post it here as an answer.
I'm going to extend @DVK's suggestion (of which I heartily approve). Based on my review of Mr. Rizos' excellent list, I would add that questions are off topic if they reference or rely on precursor knowledge that is not cited
"Why didn't the world community bake me a birthday cake? (or stop
Mugabe, or Bush, or Chavez, or whoever)?" (If you're going to ask
that, you need to define the world community in some way; give me
a wikipedia link to the UN High Commissioner on Birthday Cakes.)
"What is the consensus of historians on ...(this picture of my
goldfish)? If there is in fact a secret cabal of historians that
dictates opinions on history, nobody has informed me of it.
Questions like these are really invitations to debate. Example
"When did you stop beating your wife (e.g. What is the timeframe for
adam and eve)" If the question doesn't provide a timeframe, or
references a timeframe that is indeterminate, or a timeframe that
relies on assumptions that are not commonly accepted, then the
question is off topic - it is an invitation to write a fantasy novel.
"Can you evaluate the impact of Sujarkama's theory of mesonic
exchange entitlements on the gross national product of the Jawethi
province of Kronos under Reaganomics?" (i.e. Astoninishingly obscure
questions based on terms, concepts and papers that are not cited).
Update: @DVK's assertion lingers in my mind and forces me to clarify that the key to why I believe these to be off topic is the absence of sources/citations. If the questions are based on sources, then they're on topic. If they don't have sources, then these aren't questions about history, they're invitations to dialogue, or politics, or religion or something else. The difference between a meeting of historians and a meeting of a professional debate society is the respect and attention paid to the sources.