The reason for their higher numbers in Eastern Europe is slavery, they were enslaved for over 500 years. How this came to be is unknown, some Romanian historians suggest that the Mongols introduced this practice in the area during their invasion in the 13th century but I wouldn't be able to tell you how valid this theory is.

In Central and Western Europe policies regarding Roma people fluctuated a lot, they didn't have any long-lived status quo anywhere other than Eastern Europe. They were sometimes tolerated but pretty much all countries and city states in the area repeatedly tried to get rid of them via persecution, expelling, deportation to colonies and in the 16th century even ethnic cleansing.

Where kicking them out didn't work (such as in Spain among others), actions were being taken in the 17th and 18th century to forcibly settle, assimilate them and disperse their culture.

The fact that there's still a significant group of "gitanos" and that their culture survived despite the efforts made by Spain over hundreds of years to get rid of them really boils down to chance and resilience rather than a specific set of actions and policies.

regards first of all, I'm not an expert on the subject. I have many skills but I'm not a historian. However Andalusian am, I have always lived here and I can tell you what I know. Andalucia before the Christian conquest was Al-Andalus. That land was very tolerant, respectful and harmonious. In fact was permitted to homosexuality and transvestism (we're talking the XI century). There, Jews, Gypsies and all people were accepted. I guess that set the stage for gypsy. Subsequently a struggle against Gypsies, which was started by the (traditionally conservative and intolerant) became Christian kingdoms. Currently there are many Andalusians who resent gypsies, but gradually it will evolve until the times of Al-Andalus