Dejima ("protruding island") was Japan's lone point of contact with the West for more than 200 years during the Edo Period.
Most people with an interest in Japan know that for more than 200 years prior to the arrival of a US fleet in 1854, Japan was a closed country. This policy of national seclusion, known as sakoku ("chained country"), meant that the Japanese were prohibited from contact with outsiders. Nevertheless they were not totally unaware of Western culture and knowlege, because of Dejima.
In modern times the area around Dejima has been filled in, such that it is no longer an island, but at one time it was, as its name suggests, an island which literally protruded out into Nagasaki harbor. Originally meant to isolate Portuguese traders, Dejima was constructed by the Tokugawa bakufu in 1636. As a man-made island, it was symbolically separated from the sacred soil of Japan proper.
The Portuguese had arrived in Japan in 1549, seeking to expand Christianity and trade, and had immediately begun demanding that the daimyo allow their ships entry into Japanese ports for these purposes. Nagasaki in particular became the home of a thriving Christian population, row upon row of western-style houses, and numerous Portuguese trading posts. However, the hegemon Toyotomi Hideyoshi (1536-1598) soon came to loath Christianity, and did his best to suppress it, although trade was allowed to continue. The Tokugawa were heirs to his way of thinking, and in 1612, Tokugawa Ieyasu banned Christianity completely. Two years later, all the churches in Japan were ordered destroyed. Then in 1635, Japanese were banned from travelling overseas and the Portuguese were ordered into isolation. For this purpose, funds were appropriated from the citizens of Nagasaki to construct an island in the harbor. This was Dejima.
Finally, in 1639, the bakufu became so fearful of the influence of Christianity that they completely forbade the Portuguese (and Spanish) from any contact with Japan. This made life difficult for the Nagasaki landlords who had financed Dejima's construction and depended on rent from the buildings on Dejima for their livelihood. Partly for this reason, the Bakufu decided to transfer the Dutch traders from Hirado to Dejima in 1641. A relatively recent arrival on the scene, the ships of the Dutch East India Company had been coming to Japan since 1600. During the Shimabara Rebellion of 1637-1638, the Dutch had sided with the bakufu, which had therefore come to trust them, and thus the Dutch were given the monopoly on western trade with Japan following the expulsion of the Portuguese.
There was a bridge between Dejima and Nagasaki, but severe restrictions were placed on passage across it. However, both the bakufu and the Japanese intellectuals of the time knew that western science and medicine were advancing rapidly, and thus anyone who wanted to acquire the secrets of Western knowlege made their way to Nagasaki. The Meiji-era ideologue and educator Fukuzawa Yukichi (1834-1901) was a famous example of one of these scholars of "Dutch studies." The Western learning that these scholars gained in Nagasaki gradually spread throughout the whole country. For this reason, the Japanese were not especially confused by the influx of Western ideas following the arrival of the Americans in the 1850s - their leaders and the intellectual elite, at least, had been following developments in the West all along through their Dutch contacts at Dejima.
Although the site where Dejima used to be is now far from Nagasaki harbor due to landfilling, and was until recently indistinguishable from the surrounding neighborhoods, the site is currently being restored to its Edo Era appearance in recognition of its historical significance. The restoration is due to be completed in 2010.