Genetic time-travelers
In the ancient city of Bukhara, certain long-lived trees are evidence of an important moment in technological history. These are paper mulberries, with the scientific name Broussonetia papyrifera. Genetic analysis of these specific trees reveals a direct lineage to populations native to China. This botanical DNA evidence supports historical accounts of how the complex art of papermaking traveled from East to Central Asia. The trees are not native to Uzbekistan and required human cultivation to survive, indicating they were deliberately transported.
The history of their arrival begins after the Battle of Talas in 751 CE. Forces of the Abbasid Caliphate captured Chinese soldiers, among whom were skilled artisans. These prisoners of war brought with them the secrets of papermaking, a technology then unknown in the region. To replicate the process, they also needed the essential raw material: the inner bark of the paper mulberry. The trees growing in Bukhara today are the direct descendants of this original, imported stock, a connection to the industrial espionage of the 8th century.
The biology of a superior paper
Samarkand and Bukhara quickly became centers of paper production, and their product was prized across the medieval world for its quality. The biological properties of Broussonetia papyrifera were important for this success. The inner bark contains long, strong cellulose fibers that, when processed correctly, create a remarkably durable, smooth writing surface. The process involved stripping the bark, boiling it, and beating it into a pulp which was then formed into sheets.
The paper produced in this region, sometimes called Sultani or shoyi kogozi (silk paper), had a characteristic light-brown or yellowish tint and a silky finish that was ideal for calligraphy, as it prevented ink from bleeding. It largely replaced papyrus and parchment, which were more expensive and less practical. Genetic studies of various mulberry species, including Morus alba (white mulberry for silk) and Broussonetia papyrifera (paper mulberry), confirm a pattern of introduction from East Asia into Central Asia along the Silk Road. The paper mulberry trees in Bukhara are historical artifacts; they are the genetic artifacts of a technological revolution that changed how information was recorded and transmitted across continents.