Benalcazar himself had returned to Quito and it was not until 1538 that he was able to undertake the conquest of the upper Magdalena and those lovely plateaux and rich kingdoms which nestled on the broad top of the eastern Cordillera. In the meantime he had been forestalled by an expedition coming from the Caribbean. In 1536 Jimenez de Quesada sallied forth from Santa Marta with eight hundred men and one hundred horses. Avoiding the swampy delta of the Magdalena, he passed through the Chimilas mountains which lie east of it, and reached the solid ground of the foothills that approach the river banks some three hundred miles above its mouth. Along these he made his way through incredible difficulties and hardships, months being consumed in the journey, and his men perishing by scores from fatigue, starvation, and continual fights with the savage natives. When he reached the river Opon, he determined to climb to the plateau, near the site of Velez, where he was told that the mountain top was inhabited by a civilised race. After fighting his way through the unconquerable savages of the Opon valley he found himself in the centre of a series of lovely table-lands, many of them the beds of ancient mountain lakes whose alluvial bottoms were inexhaustibly fertile, where the climate was perfect and all the products of the temperate zone grew luxuriantly. The plateaux, interrupted by valleys and ridges, stretched from Pamplona to beyond Bogota--a distance of more than two hundred miles. This region was then and remains to this day the populous heart of Colombia, the principal seat of power, wealth, and national civilisation. However, it is so isolated that it has never constituted a nucleus around which the widely separated provinces of Colombia could unite into a well organised nation. To reach Tolima, Bogota's nearest neighbour in the upper Magdalena valley, it is necessary to descend thousands of feet of steep mountainside, along which the sure-footed mule can hardly climb. To reach Cauca, not only must the Magdalena valley be crossed but the enormously high Quindio range must be climbed, and before getting to the Pacific, still another mountain chain intervenes, while the populous gold regions of Antioquia can only be reached by following down the Magdalena and up the Cauca. Weeks of the most difficult journeying are required to get to the seacoast or any of the other states, and Panama might as well be on the other side of the globe so far as practical communication goes. [Illustration: TRAVELLERS DESCENDING A MOUNTAIN ROAD]