Time travelers? Aliens? My guess would be sloppy archeologists.
Archeologists in China are baffled after finding a tiny Swiss watch in a 400-year-old tomb. The watch ring was discovered as archeologists were making a documentary with two journalists from Shangsi town.
“When we tried to remove the soil wrapped around the coffin, a piece of rock suddenly dropped off and hit the ground with a metallic sound,? said Jiang Yanyu, former curator of the Guangxi Autonomous Region Museum.
“We picked up the object, and found it was a ring. After removing the covering soil and examining it further, we were shocked to see it was a watch.”
source: http://xenophilius.wordpress.com/2008/12/18/swiss-watch-in-400-year-old-tomb/
Gnostalgia 
Now they need to do some some research to find out if the site has been excavated before. 😉
Methinks a Victorian-era lady may have explored that tomb, which is as interesting as the tomb.
Indeed!