The old trading-posts at Guardafui, formerly under Arab control, were now free, through the quarrels of their overlords, and their markets were open to who might seek. And then a Roman subject, perhaps in the Abyssinian service, was driven to sea and carried in an open boat to India, whence he returned in a few months with a favorable wind and much information. Then Hippalus, a venturesome navigator whose name deserved as much honor in Roman annals as that of Columbus in modern history, observed the periodic change of the Indian monsoon (doubtless long known to Arab and Hindu), and boldly setting sail at the proper season made a successful trading voyage and returned with a cargo of all those things for which Rome was paying so generously: gems and pearls, ebony and sandalwood, balms and spices, but especially pepper. The old channels of trade were paralleled but not conquered; so strong was the age-long understanding between Arab and Hindu, that cinnamon, which had made the fortune of traders to Egypt in earlier times, was still found by the Romans only at Guardafui and was scrupulously kept from their knowledge in the markets of India, where it was gathered and distributed; while the leaf of the same tree producing that precious bark was freely offered to the Roman merchants throughout the Malabar coast, and as malabathrum formed the basis of one of their most valued ointments.
Great shiftings of national power followed this entry of Roman shipping into the Indian Ocean. One by one Petra and Gerrha, Palmyra and Parthia itself, their revenues sapped by the diversion of accustomed trade, fell into Roman hands. The Homerite Kingdom in South Arabia fell upon hard times, its capital into ruin, and some of its best men migrated northward and as the Ghassanids bowed the neck to Rome. Abyssinia flourished in proportion as its old enemy declined. If this state of things had continued, the whole course of later events might have been changed. Islam might never have appeared, and a greater Rome might have left its system of law and government from the Thames to the Ganges. But the logic of history was too strong. Gradually the treasure that fell to the Roman arms was expended in suppressing insurrections in the conquered provinces, in civil wars at home, and in a constant drain of specie to the east in settlement of adverse trade balances; a drain which was very real and menacing to a nation which made no notable advance in production or industry by means of which new wealth could be created. As the resources of the West diminished the center of exchange shifted to Constantinople. The trade-routes leading to that center were the old routes through Mesopotamia, where a revivified power under the
