I think the Boltons did it all through hard power and the Vlad Tepes School of Public Relations.

I think the difference between the Teagues and the Boltons is that the latter understood how to use symbolism and exemplary punishment to build compliance in the long-term (”a peaceful land, a quiet people”).
At the same time, with the Boltons, we can see the limits of that strategy – all of their regional neighbors hated and despised them, and so joined House Stark the moment the Starks showed themselves to be a viable alternative.