The long line separating the Indian and agricultural frontiers was in 1850 but little farther west than the point which it had reached by 1820. Then it had arrived at the bend of the Missouri, where it remained for thirty years. Its flanks had swung out during this generation, including Arkansas on the south and Iowa, Minnesota, and Wisconsin on the north, so that now at the close of the Mexican War the line was nearly a true meridian crossing the Missouri at its bend. West of this spot it had been kept from going by the tradition of the desert and the pressure of the Indian tribes. The country behind had filled up with population, Oregon and California had appeared across the desert, but the barrier had not been pushed away. Through the great trails which penetrated the desert accurate knowledge of the Far West had begun to come. By 1850 the tradition which Pike and Long had helped to found had well-nigh disappeared, and covetous eyes had been cast upon the Indian lands across the border,--lands from which the tribes were never to be removed without their consent, and which were never to be included in any organized territory or state. Most of the traffic over the trails and through this country had been in defiance of treaty obligations. Some of the tribes had granted rights of transit, but such privileges as were needed and used by the Oregon, and California, and Utah hordes were far in excess of these. Most of the emigrants were technically trespassers upon Indian lands as well as violators of treaty provisions. Trouble with the Indians had begun early in the migrations. [Illustration: THE WEST IN 1849 Texas still claimed the Rio Grande as her western boundary. The Southwest acquired in 1848 was yet unorganized.]