Is it possible in an era of many democratic societies and advanced technology for nations to gain power without oppressing others? that is, can nations avoid denying people their rights? explain

For me, i don't think it's possible.

Humanity always created a society where there will be an 'upper class' and 'lower class.' 
As long as this exist, Envious and hatred will always exist that will always potentially create oppression and violence.

hope this helps