Empires collapse when intolerance replaces openness.

Hear that? Suck it Ayn Rand, no one got to the moon by themselves and acting selfishly on the individual level. 

American chattel slavery has left the chat

They were not Tolerant of a Native NATION'S ! In the USA ! America wiped them out.

This is just patently untrue. Were the mongols tolerant?

Well duh. It's impossible to force so many people to follow your will without making them like you at least a little. Technology just isn't there yet

Assimilation and Accommodation are both important for any modern country, too much or too little and things start collapsing

Rome did not fall because it became intolerant. The Aztecs didn't rise to power by being tolerant.

I don’t think Louis XIV was open for change nor was he tolerant towards poor people.

This is a good message, framed in an extremely poor, hyperbolic manner that is bound to make people fight in the comments.

Do you really expect a Native American to say the USA's great strength was tolerance? Or an Irishman to say the Brits were somehow more tolerant than other powers at the time?

There are some superpowers that could be considered relatively tolerant, but the majority were just concerned with power, wealth extraction, and the domination of people they deemed lesser.

Sometimes it made business easier to overlook religious differences and such, like the Mongols did. But the Mongols still raped, pillaged and murdered enough people to change the oxygen levels in the atmosphere...

You should avoid hyperbole when talking about history because it's very rare for an absolute rule to be true.

Why do you want an empire anyway?