During Spain's 1936-1939 civil war, about 3,000 children were evacuated to the Soviet Union. Some of them are still there.
The government of the USSR helped those children retain their language and culture, and provided them with education and professional training, but - in contrast to their fellow exiles in other countries - Moscow did not allow them to return to Spain after the Civil War was over.
According to the Centro Español in Moscow, living currently in Russia are some 315 "war children," who - along with their own children, grandchildren and even great-grandchildren - form a community of 1,200 to 1,300 people. [Link]