Complex sentence: He began writing the book after migrating from England to Denmark based on his perceptions of the Nordic region before and after moving; he wanted to present an alternative perspective to the extremely positive depiction of the region in other British media.
Split into simpler sentences: He began writing the book after migrating from England to Denmark, based on his perceptions of the Nordic region before and after moving. He wanted to present an alternative perspective to the extremely positive depiction of the region in British media.