The Romani were a specific culture of humans on Earth, who's roots drew back to the country of India.
The Romani weren't grouped onto a specific continent, instead being spread out to various parts of the world. The origins of the Romani can be traced back to North India, from which they migrated from as a large group. The Romani had a tendency to be nomadic, and to adopt the ideals of the areas in which they settled. In Earth's past, the Romani were typically looked upon with suspicion and and thought to have a penchant for stealing, due to the appearance that most had been poor. Thus, the slang gypsie came about, when most referred to this culture of people. A common and widely shared belief among this culture had been to adopt children, rather than reproduce, as it had been seen as unclean.
In 2385, Doctor Beverly Crusher drew a link between the Romani people and the People of the Open Sky, who she thought shared many similarities. Specifically, of these similarities, was the fact the People had many adopted children and were looked upon with suspicion and dislike. (DS9 novel: The Missing)