The Byzantine Empire is one of the major miracles of JL history. The adjective is synonymous to-day with luxurious and corrupt decadence, yet the " decadent" Empire for more than nine hundred years held the pass against the East, and permitted the West to proceed with its task of assimilation and consolidation. Time and time again destruction threatened ; time and time again the Empire was little more than Constantinople and its suburbs ; time and time again a vigorous ruler pushed the frontiers back again to the Nile, the Danube, and the Euphrates. It was while the German invaders, planted amid alien peoples, were painfully passing from the tribal into the national state, that the first great attack was launched on the Eastern Empire. The storm came from the deserts of Arabia. It was a land of strange contrasts. Arab merchants, with bases in nourishing ports and on fertile coastlands, held the Indian Ocean trade ; they had created a state which had become a Christian state in Ethiopia (Abyssinia); they held the east coast of Africa down to Sofala; their ships were in every port from the Persian Gulf to the East Indies and the coasts of China. The sea lands of Arabia were full of prosperous little warring kingdoms which had attained a high level of civilisation. Some were Christian after a fashion, some had accepted Judaism, some were still heathen ; and behind them the desert teemed with nomads, fierce, untamable fighters. Tribesman and town dweller lived side by side and changed roles at will.