Kanazawa University archaeology Professor Tatsuo Sasaki said the vase shards found at the former location of the Heijokyo palace were proof Nara once played a role in the extensive international trading route known as the Silk Road of the Sea, The Asahi Shimbun said Monday.
During Japan's Nara Period of 710-784, Heijokyo was the country's capital.
The Shimbun said researchers suspect the 19 discovered shards came from a vase likely used to transport spices from Islamic lands.
The pieces, thought to be from a vase more than 18 inches tall, now represent the oldest Islamic ceramic vase ever found in Japan.
The previous oldest find, in Japan's Fukuoka Prefecture, was thought to have been created nearly a century after the recently discovered vase.