If we turn to Asia and examine the western race boundary of the expanding Chinese, we find that a wide belt of mingled ethnic elements, hybrid languages, and antagonistic civilizations marks the transition from Chinese to Mongolian and Tibetan areas. The eastern and southern frontiers of Mongolia, formerly marked by the Great Wall, are now difficult to define, owing to the steady encroachment of the agricultural Chinese on the fertile edges of the plateau, where they have converted the best-watered pastures of the Mongols into millet fields and vegetable gardens, leaving for the nomad's herds the more sterile patches between.[376] Every line of least resistance--climatic, industrial, commercial--sees the Chinese widening this transitional zone. He sprinkles his crops over the "Land of Grass," invades the trade of the caravan towns, sets up his fishing station on the great northern bend of the Hoangho in the Ordos country, three hundred miles beyond the Wall, to exploit the fishing neglected by the Mongols.[377] The well-watered regions of the Nan-Shan ranges has enabled him to drive a long, narrow ethnic wedge, represented by the westward projection of Kansu Province between Mongolia and Tibet, into the heart of the Central Plateau. [See map page 103.] Here the nomad Si Fan tribes dwell side by side with Chinese farmers,[378] who themselves show a strong infusion of the Mongolian and Tibetan blood to the north and south, and whose language is a medley of all three tongues.[379] [Sidenote: Boundary zones of mountain Tibet.]