its territory was part of historical east prussia (german: nord-ostpreussen), which was an exclave of germany from 1919 until 1945. that year, it was occupied by the soviet union as a result of the world war ii. the region was later annexed to the soviet union under border changes of the potsdam agreement, when it was attached to the russian soviet federative socialist republic (rsfsr). most of its german population were fled west to west germany during the last months of the war. the rest were expelled between 1944 and 1950. russian settlers were moved in and the population is now mainly russian. as of the 2010 census, only a small number of ethnic germans remain; most of the several thousand who live in the oblast are recent immigrants from other parts of the former soviet union.