XXXIV BETWEEN ROME AND CHINA

the frontiers of the imperial peace. The thrust of the Han empire from north China into Mongolia was strong and continuous. The Chinese population welled up over the barrier of the Great Wall. Behind the imperial frontier guards came the Chinese farmer with horse and plough, ploughing up the grass lands and enclosing the winter pasture. The Hunnish peoples raided and murdered the settlers, but the Chinese punitive expeditions were too much for them. The nomads were faced with the choice of settling down to the plough and becoming Chinese tax-payers or shifting in search of fresh summer pastures. Some took the former course and were absorbed. Some drifted north-eastward and eastward over the mountain passes down into western Turkestan.