The coexistence in the world has always been a problem because humans are reluctant to accept anyone who is not like them and that is why in many cases any race that is not their own is despised.
Therefore, racism arises.
Through the years there had been different kind of racism, as the famous and sad slavery of black people at hands of white people.
Nowadays, racism still exists but it is increasingly diminishing more and more because people is raising awareness.
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To my mind, the solution to this problem is just changing our mind in order to accept people who is not like us, take away our prejudices, improve our self-esteem and realise that people who is not like us must have the same rights as us because we all are humans, and we all are able to breath, think and feel.
In my opinion, it is the biggest nonsense becoming badly us to each other instead helping us to each other to lessen our problems and having a nice coexistence, what would help us to be happier than we are. Pace and mutual aid are the main tools to have a nice coexistence.