Simplify the following text for a Grade 7 native English-speaking person.
Original: Scilly has been inhabited since the Stone Age and its history has been one of subsistence living until the early 20th century ( people lived from what they could get from the land or the sea ) .
Simplified: Scilly has been inhabited since the Stone Age . Its history has been one of subsistence living until the early 20th century ( people lived from what they could get from the land or the sea ) .