Since early times, Kurotani (today's Ayabe district, in Kyoto Prefecture) has been blessed with paper-mulberry plants and the pure waters of the Kurotani River, both of which are essential for the production of Japan's famous paper ('washi'). Kurotani washi has been manufactured for a thousand years since the Heian-era. It is believed that fleeing Heike warriors invented the paper, bequeathing the tradition to future generations. During the Edo-era, Kurotani washi was recognized for its quality and evolved as a cultural artefact as well as a cottage industry. As a result, many factories were established and flourished. Later in the Edo-era, sericulture prospered and the demand for paper using silk threads increased. In the Showa-era, with the development of machine-based technologies and the widespread use of Western papers, the demand for washi diminished. Today, Kurotani is known worldwide for its traditional all hand-made washi.