Complex sentence: The land where the Darien colony was built is virtually uninhabited today although recent research has suggested that had the venture not been deliberately sabotaged by the English and Spanish governments it could have been a major economic success providing major economic competition to England and Spain.
Split into simpler sentences: The land where the Darien colony was built is virtually uninhabited today. Recent research has suggested that had the venture not been deliberately sabotaged by the English and Spanish governments it could have been a major economic success providing major economic competition to England and Spain.