There's also the power behind the throne. Cardinal Richelieu was definitely a Slytherin.
Well yes he was. But he never organized a circle of Slytherins to permanently take over France.
And don't forget how unsuccessful were Machiavelli - model of everything that is Slytherin.
How about the Vedic castes of India? Brāhmaṇa = Ravenclaw, Kṣatriya = Gryffindor, Vaiśya (later Śūdra) = Hufflepuff. Nobody admits to being a Slytherin, which is suspicious, don't you think?
Brits were playing Indians against each other extremely successfully. They took over India before anybody even noticed.
Brits
That's a much later time period than Vedic society, but I like it all the same.
Update: This post has also been superseded - new comments belong in the latest thread.
The second thread has now also exceeded 500 comments, so after 42 chapters of MoR it's time for a new thread.
From the first thread: