My question on Authenticity of the Russian birch bark manuscripts prompted me to think about the problem that one of the commentators called "state sanctioned truth"*
These are historical events, characters, old books or anything the official history has built upon, and which are wrong, fake, never existed, never happened, happened in another country and another time - you get my point. But these things are so important for current political régime, national pride, sense of unity etc that they are still alive in history textbooks and conventional wisdom of the country.
Do such things exist/existed? If yes, what are the examples of such "deceptions"?
*The manuscripts we spoke about not necessarily belong to this category