Complex sentence: Because of his Jewish origin, between the ages 10 to 15 he was not allowed to attend public schools and for three years he was doomed to be either murdered on the spot or deported to a Death camp in nearby Poland.
Split into simpler sentences: Because of his Jewish origin, between the ages 10 to 15 he was not allowed to attend public schools. For three years he was doomed to be either murdered on the spot or deported to a Death camp in nearby Poland.