Colombia, officially the Republic of Colombia (Spanish: República de Colombia), is a sovereign state largely situated in the northwest of South America, with land, and territories in North America. Colombia shares a border to the west with Panama, to the east with Brazil and Venezuela, and to the south with Ecuador and Peru. It shares its maritime limits with Costa Rica, Nicaragua, Honduras, Jamaica, Haiti, and the Dominican Republic. Colombia is a unitary, constitutional republic comprising thirty-two departments, with the capital in Bogotá. Colombia has been inhabited by various American Indian peoples since at least 12,000 BCE, including the Muisca, Quimbaya, and the Tairona, along with the Inca Empire that expanded to the southwest of the country. Spaniards arrived in 1499 and by the mid-16th century annexed part of the region, establishing the New Kingdom of Granada, with Santafé de Bogotá as its capital. Independence from Spain was achieved in 1819, but by 1830 the Gran Colombia Federation was dissolved, with what is now Colombia and Panama emerging as the Republic of New Granada. The new nation experimented with federalism as the Granadine Confederation (1858), and then the United States of Colombia (1863), before the Republic of Colombia was finally declared in 1886. Panama seceded in 1903, leading to Colombia's present borders. Beginning in the 1960s, the country suffered from an asymmetric low-intensity armed conflict and political violence, both of which escalated in the 1990s. Since 2005, there has been significant improvement in security, stability, and rule of law. Colombia is the most ethnically and linguistically diverse country per capita, with its rich cultural heritage reflecting influences by various Amerindian civilizations, European settlement, forced African labor, and immigration from Europe and the greater Middle East. Urban centres are concentrated in the Andean highlands and the Caribbean coast. Colombia is the most densely biodiverse country per square kilometer, and is part of the world's 17 megadiverse countries; its territory encompasses Amazon rainforest, highlands, grasslands, deserts, islands and coastlines along both the Caribbean and Pacific. Colombia is a transcontinental country and a regional power in the Americas. It is part of the CIVETS group of leading emerging markets and a member of the UN, the WTO, the OAS, the Pacific Alliance, and other international organizations. Colombia's diversified economy is the third largest in South America, with macroeconomic stability and favorable long-term growth prospects.