When did racism begin to be viewed as unacceptable and it was frowned upon?

racism pratically started ever since life has been around. it will probably not ever stop even if everyone turns into one race

-daddii's grlii

Actually your wrong, racism didn't exist until about the 1750's. Before then, people were never racist, just look at ancient greco-roman slavery and you'll see that they enslaved other caucasions, even African slave trade was driven by west African kingdoms.