All the carrying trade west of Calicut seems to have been in the hands of Mahommedans, by far the most part of them being Arabs, at the date of da Gama's adventurous voyage to India. It was, of course, by far the more adventurous and full of danger for that very reason, because here was he, a Christian, and therefore to be regarded as almost their natural enemy by all good Mahommedans, coming to interfere with a trade which they had made their own. It does not seem possible that they did not realise what his coming was likely to mean for the future of that trade. The Arab traders themselves knew the eastern coast of Africa at least as far south as Mozambique, for it was at this point that da Gama first came into touch with them. And it is probable that they knew the African coast further south also. They must have realised that ships going round the Cape of Good Hope could carry goods from India to Europe very much more cheaply than they could be transported by means which involved several transhipments, the payment of duties at several ports, and a longer or shorter carriage overland. The wonder is that da Gama, going with only three vessels and of no great size--they were of the kind that were known as caravels--was ever allowed by the Moslems to come home again. But he artfully pretended to them that these three were only part of a larger fleet from which they had become separated, {5} and it may be that this pretence imposed upon the Arabs and deterred them from doing him any injury. As it was, he was imprisoned for awhile by one of the Sultans, or rulers of a territory on the Indian coast, but by some means he conciliated his captor and was allowed to trade and go home again with his ships laden with silks, pearls, rubies, and a variety of treasure. The question that naturally occurs now is why it should have been the Portuguese, of all the European nations, that were led to undertake this sailing round Africa. The answer is interesting, because it involves an explanation of a curious idea of the geographers of the day.