Longer and longer journeys he took, trading shells for new dyes, flint arrow-heads, strong basket-reeds, and hides and furs of all sorts, learning more and more of the country as he trafficked. Once he found families living in a house built of stone and mud bricks, in the crevice of a cliff, getting water from a little brook at the base of it, and raising corn and vegetables along the waterside. Their houses had no real doors. They had trap-doors in the roof, reached by a notched tree-trunk inside and one outside. The corn that grew in the little farm at the foot of the cliff was of different colors, red, yellow, blue and white. Each kind was put in a separate basket. Each kind of meal was made separately into thin cakes cooked on a very hot flat stone. A handful of the batter was slapped on with the fingers so deftly that though the cake was thin, crisp and even, the cook never burned herself. The people were always on their guard against roving bands of Indians who lived in tipis, or wigwams, and were likely to attack the cliff-dwellers at any moment. Cabeca de Vaca became interested in these wandering tribes, and moved north to see what they were like. He found them quite ready to trade with him and extremely curious about his wares. They had hides upon their tipis of a sort he had not seen before, not smooth, but covered with curly brown fur like a big dog's. It was some time before the Spanish trader made out what sort of animal wore such a skin, though he knew at first sight that it must be a very large one. Finally the old medicine man with whom he was talking began to make sketches on the inside of one of the great robes. The Spaniard in his turn made sketches, drawing a horse, a goat, a bear, a wolf, a bull. When he drew the bull the old Indian got excited. He declared that that was very like the animal they hunted, but that their bulls had great humped shoulders like this--he added a high curved line over the back. Cabeca came to the conclusion that it must be some sort of hunchbacked cow, but whatever it was, the curly furry hide was comforting on cold nights. The old Indian told him a few days after that some of the young men had just come in with news of a herd of these great animals moving along one of their trails, and if the white men cared to travel with them he could see them for himself. It did not take the trader long to make up his mind. He went with the Indians at the slow trot which covers so many miles in a day, and sooner than they had expected, they saw from a little rise in the ground a vast herd of slowly moving animals which at first the white man took for black cattle. But they were not cattle.