Fray Francisco Morillo recounts his journey along the banks of the Red River, one of the most important rivers of the River Plate Basin, and one of the most remarkable of the Gran Chaco region. Running from the mountains of Santa Victoria, it empties into the Paraguay River. European settlers first took in the river 1780, when Francisco Morillo and 20 other sailors tried to find a means of transport that missionaries could use on their trips inland.