I'd say the most-tolerant race are those inhabiting the US today; we are one of very few societies & cultures in world history that can accept all nationalities, races, ethnicities, creeds, religions, etc. Which other societies can compare to US? I cannot think of any. Xenophobia and Racism are much more critical, dangerous, and blatant in any other place & society. Few world societies are accepting toward immigrants picked-off as "racial outsiders". Even fewer would allow such immigrants economic 'Opportunities'. China, for example, may allow a lot of immigrants, but would any non-Chinese, non-Asian citizen ever become a First Class Citizen? Probably not… in the US, everybody potentially can become a First Class Citizen, based-upon loyalty to the US Constitution, philosophy, and founding ideology.