Since the days of the Jesuit missionaries the Mojos Indians in the prairies on the Mamore north of Santa Cruz have retained a measure of civilisation, breeding cattle and keeping up a connection with the Creoles at Santa Cruz. Lately the latter have pressed on into the rubber regions of the lower Mamore and even crossed into the valley of the Beni and founded the town of Riveralta where the Orton joins the Beni. From La Paz daring men painfully made their way down the roadless gorges of the great Cordillera and reached navigable water where the Beni emerges from the mountains. Thence to Riveralta the way was comparatively easy and little steamboats now ply those waters. This region is permanently inhabitable by civilised man, but to the north-east the country drops off into swampy plains drained by the Acre, a tributary of the sluggish Purus. Up the latter river the Brazilian rubber hunters had come from Manaos and found the banks of the Acre unprecedentedly rich in the finest gum. Thousands poured into the territory and by the early nineties it was furnishing a large percentage of the world's supply. Though the Bolivian boundary had long been believed to cross the Acre near the 9th degree, the Brazilian rubber gatherers did not hesitate to enter an entirely unoccupied territory and even penetrated as far south as the 12th degree in a region undisputably Bolivian. The authorities at La Paz attempted to assert their political control, but since it was well-nigh impossible to get troops into the country except by way of the Atlantic, the rubber gatherers defied them. The Brazilian government intervened to protect the interests of its citizens; President Pando headed an expedition in 1902 which was met at the borders of the Acre valley, and after some fighting with the insurgent Brazilians, which seemed likely to bring on a war between the two powers, a treaty was agreed upon by which Brazil takes the territory, paying a money indemnity, agreeing to build the railroad around the Madeira Falls, and ceding a port on the Paraguay.