Complex sentence: These jewels turned into the islands and islets dotting the bay, linking together to form a great wall against the invaders; many of the rock mountains abruptly appear on the sea, ahead invaders' ships making the fast-forward ships struck the rocks.
Split into simpler sentences: These jewels turned into the islands and islets dotting the bay, linking together to form a great wall against the invaders. Under magics, numerous rock mountains abruptly appear on the sea, ahead invaders' ships; this makes the fast-forward ships struck the rocks.