Why does ignorance cause racism

Often times ignorance causes racism because you're not paying attention or really looking at another peoples' race, history and lives. 

After all, ignorance means to have a lack of knowledge or information. And if one is ignorant towards other people, we won't learn or grow as people together. We may end up - because of ignorance - hating people that could have been our lifelong friends.

I've actually never heard of the guy. but, atleast he doesn’t rap/sing about drugs and girls, but he still have a very high view of himself, which could possibly cause annoyance