Stalin forcibly moved millions of Poles and decreased Polish territory by 1/7th, that after hundreds of thousands of Poles were murdered by Ukrainians and 2 out of top 5 pre-WW2 Polish cities become Ukrainian/Lithuanian capitals.

Poles behaved very responsibly after 1989. Let's remember Poland got independent in 1989 and Ukraine/Belarus/Lithuania in 1991. There was a window of a year or so in which Poland had already organised state and army and the eastern neighbors - didn't.

It could have gone very wrong (think - Yugoslavia like) if not for the 30 years of internal discussions about the imperialism and future reconcilliation among Polish oppositional elites.