The Silk Road has promoted mutual communication between different countries and ethnic groups along the route, and promoted two-way cultural exchanges between the East and the West. The impact of the Silk Road on agriculture is also very far-reaching and continues to this day.

The exchange of crops along the overland Silk Road has been an important and fascinating scientific question for thousands of years. How various crops migrated and spread along the overland Silk Road has also been debated.

Recently, based on evidence from archaeology, genetics and genomics, researchers including Dr. Wang Guangyan from Kunming Institute of Botany, Chinese Academy of Sciences integrated the transmission routes of 207 crops along the overland Silk Road, and analyzed the transmission routes of 19 crops with genomic evidence. The route has been focused on analysis. Relevant research results were published online in the journal "BMC Plant Biology".

The overland silk road is the channel for the spread of crops from east to west

The overland Silk Road passes through many ecologically fragile regions and key biodiversity hotspots. Over 4,138 species of animals and 7,371 species of plants thrived along the long road of the overland Silk Road.

About 10,000 years ago, humans domesticated crops such as wheat, potatoes, rice, and corn. With the domestication of these crops as an important symbol, human production and lifestyle have undergone tremendous changes. On the east and west sides of Eurasia, the two earliest domestication centers in the world appeared respectively. Barley and wheat were domesticated in the fertile crescent of western Asia, known as the Fertile Crescent; while rice and millet were domesticated in China's Yangtze and Yellow River basins, respectively.

Zhang Qian's mission to the Western Regions in 138 BC marked the opening of the Silk Road. The opening of the Silk Road connected East Asia and Central Asia. After Zhang Qian's mission to the Western Regions, the communication network across the Eurasian continent was connected, which strengthened the communication between China and Central Asia, West Asia, and European countries.

"Crop exchange is an important part of the exchanges between China and the West along the Silk Road, and it has had an important impact on the production and life of people along the Silk Road." Yang Yongping, the corresponding author of the paper, director and researcher of Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, said that on the one hand, my country's traditional The spread of agricultural crops has profoundly affected the development of world agriculture; on the other hand, the introduction of crops from other regions to my country has also affected my country's crop planting structure, crop diversity, food culture and material life.

With the expansion of the Silk Road trade, some crops were spread between East and Central Asia. Crops such as rice, soybeans, and mulberries spread from China to Central Asia, while crops such as cotton and sugarcane spread from Central Asia to China. However, there is still much debate about the migration processes of many crops due to conflicting evidence between archaeology and genetics.

Analysis of the relationship between the dispersal routes of 19 crops and the Silk Road

In this study, the researchers found that the genomic evidence of five crops, barley, mustard, lettuce, buckwheat, and chickpea, clearly conflicted with archaeological and genetic evidence. Incomplete information and data, differences in records in different periods, and differences in data analysis techniques may be the main reasons for this conflict.

For barley, wheat, dates, pistachios, turmeric, alfalfa, walnuts, broccoli, grapes, spinach, apples, cucumbers, mulberries, and peas, the genomic evidence was consistent with archaeological and genetic evidence.

"We further analyzed the relationship between the transmission routes of the above-mentioned 19 crops and the overland Silk Road, and found that the four crops of highland barley, barley, wheat, and jujube spread to my country earlier than the Silk Road," Wang Guangyan said. Taking highland barley as an example, relevant evidence from archeology and genetics shows that my country's Tibet may be its domestication center. Genomic evidence shows that between 4,500 and 3,500 years ago, highland barley was introduced from the Fertile Crescent of West Asia through northern Pakistan, India, and Nepal to the southern part of Tibet, and gradually became the main food crop on the Qinghai-Tibet Plateau.

At the same time, genomic evidence shows that barley was introduced into my country from the Upper Jordan Valley about 6,000 years ago, and wheat arrived at the foothills of the Western Tianshan Mountains in Central Asia from the Upper Jordan Valley around 5,500 years ago, and then was introduced into China by the early farmers in Central Asia about 5,200 years ago. Carried by herdsmen, it went northward through the West Tianshan Mountains and entered the Altai region of Xinjiang, my country.

Jujube is a unique perennial tree species in my country, with a cultivation history of 7,000 years. According to archaeological and classic records, as early as around 100 BC, jujube trees had been introduced from my country to Korea, Japan and other neighboring countries, and then spread to Europe along the Silk Road. The results of population genome analysis showed that Shanxi and Shaanxi were the origins of jujube cultivation. The cultivation of jujube in Shaanxi was later than that in Shanxi, and it was later in East China and South China.

(Original title "Based on the evidence of archaeology, genetics and genomics, the key analysis of 19 crops found that 4 crops including wheat were introduced into my country earlier than the Silk Road")