Wow!
Would love to know the story of how it got there, the people who owned it and how it came to be preserved.
The most obvious answer would be via the Silk Road; there was a spur from the east end of the Silk Road in Xian that went through Manchuria and the Korean peninsula to Japan, ending in Nara.
1,700-Year-Old ‘Roman Glass’ Discovered In East China
http://www.freerepublic.com/focus/news/1525734/posts
Roman-Style Column Bolsters Han Dynasty Tomb
http://www.freerepublic.com/focus/news/1814182/posts
Archaeologists Uncover Ancient Maritime Spice Route Between India, Egypt
http://www.freerepublic.com/focus/news/1074033/posts
Tamil Trade
http://www.freerepublic.com/focus/chat/1213591/posts
South Indians in Roman Egypt?
http://www.freerepublic.com/focus/chat/2488786/posts?page=4#4
Buddha statue from 6th c found in Viking hoard in Helgo, Sweden
http://www.freerepublic.com/focus/chat/1391864/posts
Nestorian Tablet in China
http://www.freerepublic.com/focus/chat/1175726/posts
European Man Found in Ancient Chinese Tomb, Study Reveals
http://www.freerepublic.com/focus/news/1840126/posts