In ancient times northern Mozambique formed part of the trade network in slaves, gold and ivory between Arabs and Persians and the Bantu kingdom of Mwene Mutapa. Intermarriage between these merchants and their African slaves gave rise to a distinct Swahili culture. Portuguese involvement started in 1498 when Vasco da Gama reached Mozambique Island. By 1510 the Portuguese had control of all the former Arab sultanates on the east African coast. Portugal participated in the partitioning of Africa among the European powers in the last two decades of the 19th Century and Mozambique took its present shape on the map in 1890. Mozambique was ruled as an overseas Portuguese province. In 1964 the Frente da Libertação de Moçambique or Liberation Front of Mozambique (Frelimo), led by Dr. Eduardo Mondlane, began an armed revolt against the Portuguese rulers. The struggle was continued after his death in 1969 by Samora Moises Machel. After a military coup in Portugal in 1974, a peace agreement was concluded and on 25 June 1975, 470 years of Portuguese rule ended. Machel became president of an independent Mozambique. Asset-stripping by the fleeing Portuguese, Marxist-Leninist centralization and nationalization, and a paralyzing and five year civil war against the Resistencia Nacional Moçambicana or Mozambican National Resistance (Renamo) contributed to the country's rapid economic decay. In October 1986 President Machel was killed when his aircraft crashed. Following the collapse of the Soviet Union, Machel's successor, President Joaquim Alberto Chissano, turned to the West and post-apartheid South Africa to jump start the economy. A general peace agreement between Frelimo and Renamo led to the adoption of a new democratic constitution in 1994. In November 1995, Mozambique was the first non-former-British colony to become a member of the Commonwealth. In 2005 Chissano was succeeded as head of state by businessman Armando Guebuza.