HEI RIVER

Wade-Giles romanization Hei Ho, Pinyin Hei He river rising in central Kansu province, China, and flowing into the western Ala Shan Desert in western Inner Mongolia autonomous region. The river is formed by a series of small glacier-fed rivers flowing north from the Nan and Ch'i-lien mountain ranges in Kansu, between Chang-yeh and Chiu-ch'an. It then flows northward across the desert into a depression filled with salt marshes and swamps that vary greatly in size from one season to another. Between Ting-hsin and Hsi-miao it is called the Jo River. At Hsi-miao in Inner Mongolia the river bifurcates into two streams, the Hsi and Tung rivers, which empty, respectively, into Lakes Ka-shun and Su-ku. The Hei Valley is virtually the only part of the Ala Shan plateau that has any permanent agriculture or permanent population. It was colonized on a small scale as long ago as the 1st century BC; its permanent settlement is comparatively recent. Even with irrigation, however, which is imperative in the arid climate of the area, the intense salinity of the soil is a major problem for agriculture. The lower course of the Hei River from about 102 BC formed a forward defense line for the armies of the Han dynasty (206 BC-AD 220), defending the region against the nomadic Hsiung-nu. In 1930-31 a Sino-Swedish expedition in the area discovered great numbers of documents written on wooden strips and dating from the period before the Later Han (AD 23-220). Most of them date from 73 to 48 BC and are the earliest surviving Chinese official documents.