The particular forms which the denominations have taken on have been shaped by immigration of the Ashkenazi Jewish communities, once concentrated in eastern and central Europe, to western and mostly Anglophone countries (in particular, in North America). In the middle of the 20th century, the institutional division of North American Jewry between Reform, Conservative, and Orthodox movements still reflected immigrant origins. Reform Jews at that time were predominantly of German or western European origin, while both Conservative and Orthodox Judaism came primarily from eastern European countries.