The climate of this basin-land of Manchuria is continental in its temperature regime and monsoonal in the seasonal distribu tion of its rainfall, thus reflecting its proximity to Central Asia and its position on the northern margins of China. Hot summers succeed intensely cold winters and light southerly breezes the northerly blasts of winter. Midsummer temperatures are uni formly high averaging 70-75° F as compared with 8o° F in China Proper and in the depth of winter the variation is only in the degree of cold. The temperature of Dairen at the tip of the Liaotung peninsula falls to 24° F and of Harbin in the central plain to below zero. The rivers are all frozen over, in the north until the end of April and even in the south until the beginning of April. Only the ports, Pont Arthur and Dairen, at the tip of the Liaotung peninsula are free from ice all the year round. This enhances immeasurably their strategic significance. Practically the whole of the rather scanty rains fall in the summer months, the time when they are of most agricultural value. The rainfall is heaviest in the East Manchurian Highlands, decreases westwards toward the foot of the Great Khingan, and is least in what is now north-western Fengtien but was long part of Mongolia and is still known as the Eastern Gobi. The average rainfall of the central plain, agriculturally the most valuable part of the country, is between 20 and 25 inches.
The effect of the Manchurian plain, encased by hill-masses, is heightened by its open steppe vegetation in contrast to the forests of the East Manchurian Highlands, of the Amurian lowlands and the Little Khingan, and of the scarp face of the northern Great Khingan. But the woods clothing the Manchurian face of the northern Great Khingan disappear on its Mongolian slope and do not interrupt the continuity of the belt of steppe which stretches across Eurasia to its eastern terminus in the Man churian plain. The extreme south-west of the central plain— the Eastern Gobi—is in part covered with sand-dunes and be tween the Liao and Nonni forms a region of inland drainage. The lowland corridor reaching down to the Gulf of Liaotung is richer grassland. The forests of the East Manchurian Highlands and Amuria, like those of the northern Appalachians and the St. Lawrence valley in North America, contain both coniferous and deciduous species. Oak, elm, and poplar clothe the lower slopes and fir, pine, spruce, and larch reach up to the hill-tops. These forest resources have especial value in view of the treeless char acter of North China and of the shortage of large timber in Japan. In the Amurian lowlands only scattered copses interspersed with meadow remain and the forests of the Eastern Highlands, even those remote from Chinese agricultural colonization, are being cut into for commercial lumber.
The Tungus of the forest retained their old hunting nomadic life but those of the central and southern plains in time acquired the arts of cultivation, probably from their Chinese neighbours, and, according to Chinese annals, were already dependent by the first millennium A.D. on the "five kinds of cereal." Although ex cellent horsemen as befitted dwellers on the steppe, the Tungus of the plain, as evidenced by the Manchus, were ignorant of the art of milking and were essentially not pastoral nomads. True pastoral nomads of Mongol affinities did however occupy the drier western part of the Manchurian steppe adjacent to Mongolia.
Until the final victory of the Manchus in the early 17th century first one group and then another gained the upper hand and for a time dominated Manchuria. Now, Manchuria is the north-eastern antechamber of China and the Power holding it is in a unique position for the invasion of the Celestial Empire. On three occasions has this position been utilized by steppe-land dynasties—by the Khitan Tatars in the loth, by the Kin Tatars in the 12th, and by the Manchus in the early 17th centuries. The Manchu dynasty when on the imperial throne (1644-1911) con tinued to regard Manchuria as the recruiting ground for the garri sons with which it held China.
The immigration of Chinese was long forbidden but after 1776 this prohibition was relaxed in the case of Fengtien, the southern province, and in the third quarter of the i9th century the Manchus had to recognize colonization in Kirin. The dense agri cultural population of North China was beginning to spill over in considerable numbers into vacant lands whose settlements, always sparse, had been further depleted by recruitment for the Manchu garrisons in China. By the end of the i9th century the population of Manchuria is estimated to have reached 14, 000,000 of which 8o% were Chinese. In comparison with what was to follow this movement, however, was no more than an infiltration and consisted mainly of males who intermixed with the Manchus and in time absorbed them. At the present day pure Manchu groups remain only in northern Manchuria, chiefly in the Aigun district, and these are the descendants of soldier colonists planted by the early Manchu emperors in the Amur valley. The rapid economic development of South Manchuria under Japanese auspices after 1905 and the security which it offered in contrast to the turmoil of China, rent by civil war and ravaged in the north by frequent famines, set in motion a mass migration of prodigious magnitude. Coming mainly from Chihli (Hop-eh) and Shantung, the most densely peopled provinces of North China, this for some years involved 300,000-400,000 annually, but of these half or three-quarters used to return to China after the Manchurian harvest. In the 1920's this seasonal migration of labourers became a permanent migration of families which amounted in 1927 to more than 800,000 and in the summer of 1928 to 40,000 a week. These Chinese peasant-farmers pene trated inland along the railways and settled in central as well as in southern Manchuria, along the Chinese Eastern as well as along the South Manchurian railway. They constituted quite 90% of the total population which was estimated in July 1927 at 24,500,000. Population is of course densest in the plains of South Manchuria and in the eastern part of the central lowland, traversed by the rail way leading towards Harbin. The Japanese, a small minority in spite of recent attempts to encourage their immigration, are chiefly in the South Manchurian ports and along the railways. A number of Russians are in the trading marts bordering the former Chinese Eastern railway. In both cases this foreign population is mercantile and administrative rather than agricultural.