Cattle caused the first settlers to penetrate these hostile regions, as the great herds began to advance into unexplored lands, bathed by rivers with clear waters. It was the São Francisco River that first brought explorers up to the vast interior. At the point where the Rio Grande flows into the São Francisco a small settlement called Barras took root. By 1600 adventurers had made their way up the Rio Grande as far as rocks that impeded their further passage. Below these rocks, "barreiras" in Portuguese, a small community began. The Rio Grande was navigable by small boats, and traders soon arrived in the region to support the cattle industry and the ranches. The village became an agricultural center producing tobacco, beans, corn and manioc. These were exported together with molasses, rum, manioc meal, and leather while European articles, kerosene and coffee were imported – all commerce being conducted by river.