If God really wanted all races to be together and "mixed" which I do not think is right, then why didn't he make us all one race?
According to the Bible, God did make us all one race. The only account of the creation of man, in Genesis 1 and 2, tells of creating one man and one woman. From them came all the rest of mankind. The races evolved over time. If they came about before Noah’s time, then it is probable that his sons were in “mixed” marriages. If they had not developed before Noah, then God clearly did not create the races, because all mankind could be considered traceable back to Noah and his family.
If all mankind was created by God, and he called his creation good, then God could have no possible objection to marriages between the races. As far as he is concerned it would appear that man is man, with no racial distinctions.