Complex sentence: During April and May 1839, British and American dealers surrendered 20,283 chests and 200 sacks of opium which was publicly destroyed on the beach outside of Guangzhou.
Split into simpler sentences: During April and May 1839, British and American dealers surrendered 20,283 chests and 200 sacks of opium. The stockpile was publicly destroyed on the beach outside of Guangzhou.