Simplify the following text for a Grade 9 native English-speaking person.
Original: The pug 's popularity spread to Tibet , where they were mainly kept by Buddhist monks , and then went on to Japan , and finally Europe . The exact origins of the pug are unknown , as Emperor Qin Shi Huang , the first Emperor of China , destroyed all records , scrolls and art related to the pug at some point during his reign which lasted between 221 and 210 BCE .
Simplified: The pug 's origin is unknown because the first Emperor of China destroyed everything related to the pug in his reign .