Rivers constituted, in the Middle Ages, the most important means of inland transport. Most of our oldest towns or cities that were not on the route of one of the Roman roads were set up alongside or within easy reach of some tidal or navigable stream in order, among other reasons, that full advantage could be taken of the transport facilities the waterways offered. So were monasteries, castles, and baronial halls, while the locating of the universities of Oxford and Cambridge on the Thames and the Cam respectively rendered them accessible by sea and river to Scottish and other students from the north who could hardly have made their way thither by land.[3] It was, however, only a limited number of inland places that could be reached by water, and other towns or settlements were wanted. The trading opportunities of the latter were at first restricted to the packhorse, few of the roads being then adapted for even the most primitive of agricultural waggons. Long lines of packhorses, with bales or panniers slung across their backs, made their way along roads or bridle paths often inadequate to allow of two strings of loaded horses to pass one another, so that many a quarrel arose, when two teams met, as to which should go into the mud to allow the other to pass along the path proper. Traders sending wool or other commodities by the same route were in the habit of making up companies in order to secure mutual protection against robbers, and they armed themselves and their servants as if going to battle. Like precautions were taken by merchants from the north when they started on their annual business journeys to {16}London--journeys so full of peril that they were not begun until the merchant had made his will and earnestly commended himself to the protection both of St. Botolph and of his own patron saint. The "commercial travellers" of that day carried their samples or their wares in a bag lying across their horse's back, thus qualifying for the designation of "bagmen" by which they were to become known. In the Middle Ages everyone rode except the very poor, and they had to be content to trudge along on foot. Kings and nobles, princes and princesses, gentlemen and ladies, merchants and bagmen all travelled on horseback. Women either rode astride until the introduction of side-saddles, in the fourteenth century, or else rode in pillion fashion. The main exception to riding on horseback, in the case of ladies or of the sick or infirm, was the use of litters attached to shafts to which two horses, one in front and one behind the litter, were harnessed. Sometimes, also, "passengers" were carried in the panniers of the packhorses, instead of goods. Certain main routes, and especially those favoured by pilgrims--such as that between London and Canterbury--must have been full of animation in those days; but, speaking generally, no one then travelled except on business or under the pressure of some strong obligation.