Bolivia is a country in South America, bordered by Brazil to the north and east, Paraguay and Argentina to the south, Chile to the west, and Peru to the west. The cultural development of what is now Bolivia is divided into three distinct periods: pre-Columbian, colonial, and republican. Important archaeological ruins, gold and silver ornaments, stone monuments, ceramics, and weavings remain from several important pre-Columbian cultures. Major ruins include Tiwanaku, Samaipata, Inkallaqta and Iskanwaya. The country abounds in other sites that are difficult to reach and hardly explored by archaeologists.