Simplify the following text for a Grade 6 native English-speaking person.
Original: Through his often-suppressed writings , he helped to raise global awareness of the Gulag , the Soviet Union 's forced labor camp system â `` particularly in The Gulag Archipelago and One Day in the Life of Ivan Denisovich , two of his best-known works .
Simplified: With his works , the Gulag , a Soviet labor camp , became well known .