The Khitan under the "One Country, Two Systems" policy introduced watermelons using greenhouses!

The Grassland Silk Road, the northernmost route connecting Eurasia via the steppe, served as both a meeting point for nomadic and agrarian civilizations and a bridge for dialogue between Eastern and Western cultures. The Qin Dynasty's construction of the "Straight Road" laid its foundation, while the Han Dynasty's silk trade with the Xiongnu thrived along this route. The Northern New Route flourished during the Wei and Jin periods, and the Tang Dynasty's "Path to the Heavenly Khan" extended its influence far and wide. The Upper Xiajiadian Culture (11th–7th century BCE) yielded artifacts like flat-headed bronze swords and bronze deer plaques, similar in style to those from Arzhan Kurgan 2. Later, the southeastern Inner Mongolia region was gradually occupied by the Donghu, ancestors of the Khitan people. The Scythians, a nomadic people active on the Eurasian steppe from the 9th century BCE to the 2nd century CE, influenced the art of the Ordos, Xiongnu, and Xianbei peoples with their symmetrical twin-horse deities, exaggerated antler motifs, and scenes of predators attacking herbivores. The Pazyryk Culture (5th–3rd century BCE) exemplified the multicultural exchange along the Grassland Silk Road. During the Liao, Song, Western Xia, Jin, and Yuan dynasties, the Grassland Silk Road reached its zenith. Liao Taizu Abaoji launched multiple western campaigns, expanding the empire's reach to the Hexi Corridor under Empress Dowager Chengtian. Gaochang, Qiuci, and other states submitted to Liao rule. The Northwest Route Pacification Office and Zhenzhou were established to safeguard the Silk Road. The Liao envoys popularized the term "Cathay" (Kitaia, Cathaia, etc.) as the common name for China in Central Asia. Meanwhile, the Western Xia controlled the Hexi Corridor, turning it into a trade hub, while the Song Dynasty frequently engaged with Central Asia via the Grassland Silk Road. The Liao-era Grassland Silk Road started from Shangjing (south of present-day Lindong Town, Bairin Left Banner, Chifeng, Inner Mongolia), Zhongjing (present-day Daming Town, Ningcheng County, Inner Mongolia), or Nanjing Xijin Prefecture (present-day Beijing) to Duolun. From there, it ran westward along the Yin Mountains to Xijing Datong Prefecture (present-day Datong, Shanxi), crossed the Hetao region, passed through Juyan to Yizhou (present-day Hami), then via Gaochang and the Tang-era Beiting (present-day Jimsar) to Ili, reaching Suyab and the northern regions of the Samanid Empire. The Khitan sacrificed white horses and black oxen. The Liao Ancestral Mausoleum is located in Bairin Left Banner, Chifeng, Inner Mongolia. The Liao Dynasty established a state-run pastoral system and developed a thriving silk industry, with specialized sericulture and weaving zones in the Daling River basin. The imperial workshops in Shangjing and Zuzhou produced brocades and damasks using silk tribute from sericulture households. Hemp cloth was widely produced, used for taxes and even as currency. After Liao Shizong relocated captured households from Dingzhou to Hongzheng County, Yizhou, Zhongjing, Liao ceramics flourished, creating unique artifacts like the cockscomb flask, chicken-leg jar, phoenix-head vase, and crabapple dish. After the Liao banned horse sacrifices for burials, gold and silver horse trappings replaced them. Khitan saddles, Duan inkstones, Shu brocade, and Ding porcelain were hailed as the "Four Finest Under Heaven." Khitan horse trappings inherited the belt culture of the Turks and Uyghurs, innovating with jade-adorned saddles and harnesses. Xuanhua (then Guihua Prefecture under the Liao) served as a vital hub connecting Yan and Yun, where nomadic and agrarian cultures intermingled. The Yuan Dynasty built a postal road network linking Dadu, Zhongdu, and Shangdu, fostering commerce through tax exemptions. Qiu Chuji, the Taoist master, traveled the Grassland Silk Road to meet Genghis Khan. During the Southern Song, Hong Hao successfully introduced watermelon seeds to the Central Plains. Meanwhile, the Khitan obtained watermelon seeds from the Uyghurs and cultivated them using "cow dung-covered greenhouses"—an early form of agricultural greenhouse technology!