Complex sentence: In 2044 a major nuclear war between the USSR and the West wipes out most of the Northern Hemisphere, leaving Brazil as the main world power, which then claims that "Space is a province of Brazil".
Split into simpler sentences: In 2044 a major nuclear war between the USSR and the West wipes out most of the Northern Hemisphere. Brazil is left as the main world power, which then claims that "Space is a province of Brazil".