A collage made by me from different pictures: map of Northern tracks to Japan via Korea, below from left: part of the hilt, Silla period crown, glass bowls from Shosoin.
The period I'm focusing on is called Unified Silla in Korea (668 - 935), and Nara in Japan (710 - 794). Actually I'm more interested in Nara period especially the sculpture from it. Yes, Ashūra, my lovely, beloved Ashūra from 興福寺. So gracious, so beautiful... wait, where was I? Ah, yes. I don't want to write on Silk Road actually, but focus on the relations and influences between those two countries. Japan has just established herself as a country based on law (adopted from China, pity it didn't work out), Silla was in full bloom.
To read more on Silla or Nara periods, just go to:Shōsoin

Tōdaiji
Imperial Household Agency - Shosoin Website: http://shosoin.kunaicho.go.jp/
Other website: http://aris.ss.uci.edu/rgarfias/gagaku/shosoin.html
List of all the items: http://reijiy.hp.infoseek.co.jp/shosoin/shosoin.html
Shosoin in Yomiuri (Japanese): http://osaka.yomiuri.co.jp/shosoin/index.htm
Shosoin in Yomiuri (English): http://www.yomiuri.co.jp/dy/features/0008/
Shosoin in Yomiuri (Japanese): http://osaka.yomiuri.co.jp/shosoin/index.htm
Shosoin in Yomiuri (English): http://www.yomiuri.co.jp/dy/features/0008/
Japanese society at that time was more open and cosmopolitan than later on. When in 894 AC, Japan stopped envoys to China, influences from the continent ceased. Contacts were cut off, but Japan started to modify everything that had been adopted since then.
Nara (Heijo-kyo) was a city where traders from different parts of Asia met. Chinese, Koreans, Japanese, merchants from South-East countries, they all conducted their interests there. That is why in Shōsoin we can see so many items from around the world, even from Rome and Persia (glass beads).
Nara, as a capital, lived for only 74 years (including sometimes 4-years breaks in presence of Emperor in it). Pressure from great Buddhist temples (sects) was so ominent, that Emperor sought the only one way out - moving the capital somewhere else.
The first years of Heian period - they are just a continuation, nothing changed. As I said, after 894, Japan closed from contacts.
Copy of Gakkiron(End Part and Signature) written by Empress KOMYO
光明皇后臨 楽毅論 末尾と自署, ACE756, 高25.6cm 紙本墨書, 正倉院,
Few items from Shōsoin:
biwa
glass bowl (one of the most famous items, proving how Japanese trade contacts were once wide and open
laquered table
chest
shakuhachi
other side of bronze mirror
horse saddle