Passage: Shirakami-Sanchi (白神山地) is a UNESCO World Heritage Site in the Tōhoku region of northern Honshū, Japan. This mountainous area includes the last virgin forest of Siebold's beech which once covered most of northern Japan. The area straddles both Akita and Aomori Prefectures. Of the entire 1,300 square kilometres (500 sq mi), a tract covering 169.7169.7 square kilometres (65.5 sq mi) was included in the list of World Heritage Sites in 1993. Fauna found in the area includes Japanese black bear, the Japanese serow, Japanese macaque and 87 species of birds. The Shirakami-Sanchi was one of the first sites entered on the World Heritage List in Japan, along with Yakushima, Himeji Castle, and Buddhist Monuments in the Hōryū-ji Area in 1993. Permission is needed from Forest Management to enter the heart of the Shirakami-Sanchi.

Question: In what year was the mountainous area added to the World Heritage Site?
1993