It was no stately procession that wound up into the hills yearly to supply the Mexican frontier. From Vera Cruz the port of entry, through Mexico City, and thence north along the highlands through San Luis Potosi and Zacatecas to Durango, and thence to Chihuahua, and up the valley of the Rio Grande to Santa Fé climbed the long pack-trains and the clumsy ox-carts that carried into the provinces their whole supply from outside. The civilization of the provincial life might fairly be measured by the length, breadth, and capacity of this transportation route. Nearly two thousand miles, as the road meandered, of river, mountain gorge, and arid desert had to be overcome by the mule-drivers of the caravans. What their pack-animals could not carry, could not go. What had large bulk in proportion to its value must stay behind. The ancient commerce of the Orient, carried on camels across the Arabian desert, could afford to deal in gold and silver, silks, spices, and precious drugs; in like manner, though in less degree, the world's contribution to these remote towns was confined largely to textiles, drugs, and trinkets of adornment. Yet the Creole and Mestizo population of New Mexico bore with these meagre supplies for more than two centuries without an effort to improve upon them. Their resignation gives some credit to the rigors of the Spanish colonial system which restricted their importation to the defined route and the single port. It is due as much, however, to the hard geographic fact which made Vera Cruz and Mexico, distant as they were, their nearest neighbors, until in the nineteenth century another civilization came within hailing distance, at its frontier in the bend of the Missouri. The Spanish provincials were at once willing to endure the rigors of the commercial system and to smuggle when they had a chance. So long as it was cheaper to buy the product of the annual caravan than to develop other sources of supply the caravans flourished without competition. It was not until after the expulsion of Spain and the independence of Mexico that a rival supply became important, but there are enough isolated events before this time to show what had to occur just so soon as the United States frontier came within range. The narrative of Pike after his return from Spanish captivity did something to reveal the existence of a possible market in Santa Fé. He had been engaged in exploring the western limits of the Louisiana purchase, and had wandered into the valley of the Rio Grande while searching for the head waters of the Red River. Here he was arrested, in 1807, by Spanish troops, and taken to Chihuahua for examination. After a short detention he was escorted to the limits of the United States, where he was released. He carried home the news of high prices and profitable markets existing among the Mexicans.