In the sixth, century a.d. Chinese and Persian merchants used to meet regularly in Ceylon for the exchange of their products: this is clear from Cosmas Indicopleustes, xi, 336, and Procopius, Persian Wars, i, 20, 9–13. In addition to this the existence of direct sea-commerce between the Sassanid Empire and China has often been asserted as an established fact, e.g. by J. T. Reinaud, Relations des voyages faits far les Arabes, etc. (Paris, 1845), p. xxxv; H. Yule, Marco Polo (London, 1903), p. 83; L. Caetani, Annali dell'Islam (Milan, 1905–1926), ii, 2, 12 A.H., sect. 133, note 1; iii, 16 A.H., sect. 328; E. H. Warmington, The commerce between the Roman Empire and India (Cambridge, 1928), pp. 138, 358, note 146; and others. But this assertion rests on slender evidence and requires discussion. I shall endeavour to set down all the passages which might be adduced and to assess the value of each one.