( ( After ( the ( World ( War I ) ) ) ) ( , ( ( the ( Roma people ) ) ( ( ( ( formed ( an ( ethnic community ) ) ) , ) ( living ( on ( ( the ( social periphery ) ) ( of ( the ( mainstream population ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN After) (NP (DT the) (NNP World) (NNP War) (NN I))) (, ,) (NP (DT the) (NNP Roma) (NNS people)) (VP (VBD formed) (NP (DT an) (JJ ethnic) (NN community)) (, ,) (S (VP (VBG living) (PP (IN on) (NP (NP (DT the) (JJ social) (NN periphery)) (PP (IN of) (NP (DT the) (NN mainstream) (NN population)))))))) (. .)))
After the World War I, the Roma people formed an ethnic community, living on the social periphery of the mainstream population.
(ROOT (S (NP (NP (NNS Populations)) (VP (VBG living) (PP (IN in) (NP (CD one) (NN place))))) (VP (VBP form) (NP (DT a) (NN community))) (. .)))