Recent times were largely the result of an unusually unipolar (read: US) world after the USSR collapsed.
In more normal bi- or multi- polar periods (50s - 90s), international order often submitted to great power politics. What was right or legal was less important than who wanted what.
I'd argue the good times were a result of the massive transfer of wealth from the wealthy to the middle classes that was caused by the two world wars. Since the neoliberal shift of politics in Western powers in the 70s, we have been on a slow return back to the crazy levels of inequality that rival any of those ever seen prior to 20th century. We are now reaping what was sown by the Thatcher/Reagan privatisation and financialisation of everything in the economy. Takes a while for the effects to really kick in but I think much of the geopolitical dynamics we are seeing can be traced back to this.
In more normal bi- or multi- polar periods (50s - 90s), international order often submitted to great power politics. What was right or legal was less important than who wanted what.