Complex sentence: The film ultimately grossed $18--$22 million in worldwide rentals and is sometimes proclaimed as the most successful film of the silent era, although it is most likely this record falls to "The Birth of a Nation".
Split into simpler sentences: The film ultimately grossed $18--$22 million worldwide. It is sometimes proclaimed as the most successful film of the silent era, although it is most likely this record fall to "The Birth of a Nation".