I am curious as to the history of the discrimination of the Romani ethnic group in European history. I do know that they were slaves in Romania for several years and in order in maintain that social order there needed to be serious prejudice in society, which has likely spread through the generations culturally as a part of social consciousness to where it is today, I would say. What do you know /r/AskHistorians?
Through genetic and linguistic research it has been most commonly established that the Roma as an ethnic group migrated from India to Europe in the 11th century. All of the research I did for a couple of papers back in M.A. pointed that they had been discriminated basically since then. Their marginalized status today makes a bit more sense given this millennium long discrimination. People wonder why it is so difficult for them to assimilate. Well that's why.