A chain of volcanoes runs across this region, creating vast fertile plains to the east, while the rugged Pacific shore to the west is serrated by deep bays. Attracted by the abundance of natural resources, the matriarchal Matambú people established fishing communities around 500 AD; they later moved inland, leaving a legacy of superb artisan pottery that continues in the Guaitíl area. Guanacaste was colonized by Spanish sabaneros (cowboys) in the mid-1500s, under the rule of Nicaragua, marking the start of a proliferation of grand haciendas, many of which can still be seen around Santa Cruz and Liberia. In 1825 Guanacaste seceded from Nicaragua and joined Costa Rica; the resulting border disputes remained unresolved until the boundary treaty of 1896. Cattle culture caused heavy deforestation throughout the 20th century. A slow trickle of conservation efforts, beginning in the 1970s, became a flood by the 1990s; the region now contains four national parks, as well as wildlife refuges and other nature reserves.