The southern half of the American land mass, connected to North America by the Isthmus of Panama, bordered by the Atlantic Ocean to the east and the Pacific Ocean to the west. Amerindian civilizations in South America included that of the Chavin and the Incas, who flourished before Europeans arrived. Colonized largely by the Spanish in the 16th century (although the British, Dutch, and Portuguese were particularly active in the north-east), much of the continent remained part of Spain’s overseas empire until liberated under the leadership of Bolivar and San Martin in the 1820s. Both culturally and ethnically the continent is now a mixture of indigenous Indian and imported Hispanic influences, modified slightly by North European and North American penetration in the 19th and 20th centuries. Although many South American countries are still hampered by economic underdevelopment, a minority have emerged as world industrial powers in their own right.