Not entirely true.  Yes, human migration, and hegemony are ubiquitous, that is a historical fact.  However, where your argument stumbles is in using this as a reasonable behaviour, especially when done in a particularly aggressive way.
The difference being made from today, to those actions in the past, is that we can be better than that.  All sorts of actions have long-standing in the history of mankind, but this is not an excuse to continue them today and forever.  
There is no going back, per se, but we can learn from our mistakes, and the ongoing damage, can we not?  And if yes, the question is, do we have a moral obligation to mitigate this damage?
Most Canadians would answer "yes", to both of those questions.