One wrong action and you could change the way your race is viewed

In todays world stereotypes are widely know by most people, and for good or bad they are there. How did they get to be so well known? Some examples are Asians are smart, African Americans like  fried chicken and are athletic. We all assume these things when we think about it, but why?. I think the reason we use stereotypes abroad is because of the influence media has on us. When you watch TV, you hear on the news of new research out of Asia proving a math theory or see a commercial with Chad Ochocinco in it. Then you watch a movie and see a Sunday afternoon lunch of fried chicken. We see stuff on TV, on the internet, in the paper and we automatically assume its true for everyone. I guess the major flaw is that we assume, we all know what happens when we assume.