It's a balmy spring day in Shimane Prefecture, but one step into the newly reopened Okubo Shaft of the Iwami silver mine and your body is enveloped by the darkness and the cold. In these eerie surroundings, it's not hard to imagine encountering the ghosts of the miners whose labor helped reshape Japan and Asia in the 16th and early 17th centuries, often at the cost of their lives.

The mine, an hour west of Izumo city, became Japan's newest World Heritage site last year primarily because of the commercial and cultural impact its massive output had over the four centuries the mine was in operation. During the area's heyday in the early 17th century, Japan produced a third of the world's silver, half of which came from the Iwami mine. The high-grade silver fueled a trading boom, with the precious metal exchanged for cotton textiles, porcelain, raw silk and copper coins from China and Korea, and spices, incense and sugar from Southeast Asia. Most of the silver went to China, where it was used as currency. European explorers and missionaries also sought out this "kingdom of silver," radically altering Japan's political and social landscape with the introduction of firearms and Christianity. This influx of foreign culture ultimately drove the nervous shogunate to close Japan's borders for 220 years.

Although the silver is long gone, the well-preserved remains of Iwami's mining production — shafts, refineries, castles and ports — are drawing tourists to the site and bringing life back to the area.