Tibet is not Mongolian - they've now got connections in terms of their religious background, but Tibetan is part of the Sino-Tibetan language family, while Mongolian is, unsurprisingly, in the Mongol language family (or if you accept the Altaic hypothesis, it's also part of the larger Altaic family with Turkic and Tungusic languages).
And what's more, take a look at the current state of Mongolia some time - it's a functioning democracy with pretty decent respect for civil liberties and no tendency to invade their neighbors. Yes, there's a long history of semi-nomadic tribes coming out of Central Asia and invading the civilized cultures along the edges of the Eurasian steppes, but that pattern wasn't unique to the Mongols (various Indo-European, Turkic, Tungusic (i.e., Manchu), Magyar and other peoples have played that role over the millennia), and that's been a thing of the past since horse archers became ineffective in war (i.e., once firearms were widespread).
And what's more, take a look at the current state of Mongolia some time - it's a functioning democracy with pretty decent respect for civil liberties and no tendency to invade their neighbors. Yes, there's a long history of semi-nomadic tribes coming out of Central Asia and invading the civilized cultures along the edges of the Eurasian steppes, but that pattern wasn't unique to the Mongols (various Indo-European, Turkic, Tungusic (i.e., Manchu), Magyar and other peoples have played that role over the millennia), and that's been a thing of the past since horse archers became ineffective in war (i.e., once firearms were widespread).