[1] The ruins of the kōrokan in Fukuoka were discovered on the grounds of Maizuru Castle Park in 1987 and designated a National Historic Site in 2004.

The year after the Battle of Hakusukinoe (664), administrative functions were moved inland to Dazaifu, and the former site on the banks of the Natsu river remained as base for overseas exchange and national defense.

The distance between the "Kōrokan" and Dazaifu is about 16 kilometers, and a straight road complete with gutters with a maximum width of 10 meters was constructed to connect the two.

Under the Ritsuryō system, the Kōrokan was under the jurisdiction of the Ministry of Ceremonies and was also used for inspections, entertainment, and trading with foreign merchants.

In (858), Enchin, a monk who studied abroad, returned to Japan on a ship run by the merchant Li Yanxiao, and the "Onjo-ji Temple Documents" states that a welcoming banquet was held at the gate tower of the north building of Kōrokan.

However, Nakayama Heijirō, a professor at Kyushu Imperial University, proposed that the site was actually under Fukuoka Castle after examining the descriptions in the Man'yōshū.

At the time, the 24th Imperial Japanese Army Infantry Regiment was stationed at Fukuoka Castle, but in 1915, on a rare "open house" day, Nakayama surveyed the barracks and collected ancient roof tiles.

A military officer in the same regiment, Kagamiyama Takeshi, also collected fragments of ancient roof tiles while guarding an ammunition depot, and the two later founded the Kyushu Archaeological Society in 1930.

The stadium closed in 1997, and full-scale excavation work began in 1999, when the stands and other buildings were dismantled, and continues to this day, and in May 2004 it was designated as a national historic site.

Ancient documents, such as the Nihon Shoki state that a "Naniwa no Murotsumi" was located at the port as a diplomatic facility, and it was here that envoys from King Muryeong of Baekje stayed in 512 AD.

[6] In April 608, Pei Shiqing, an envoy of Emperor Yang of Sui was welcomed by the Imperial Court at this location, thus marking the start of diplomatic relations between Japan and China.

When the imperial capital moved to Heian-kyō, modern day Kyoto, in 794, a kōrokan was initially built on both sides of the Rajōmon the south gate of the city.

In the Kōnin era (810–824) it was removed due to the construction of the great temples of Tō-ji and Sai-ji, and replaced by an east guest house on Shichijō, southeast of what is now Tambaguchi Station in Shimogyō-ku, Kyoto.

In 824, the Udaijin Fujiwara no Otsugu declared that the envoys from Balhae were merchants, and not diplomats, and from thence the frequency of official visits was reduced to every 12 years.