Here are some details about the bowl: http://ajw.asahi.com/article/behind_news/social_affairs/AJ201408010029
In 500 AD, the Sassanid empire controlled Samarkand and cooperated with the Jin dynasty to keep the Silk Road through Central Asia open and safe for travel. The Persians traded with the Han dynasty, so the Sassanid were merely continuing a long tradition. This glassware had around 300 years to get into China, then make its way to Japan.