Trading posts were established, most notably slave trade, and the town of Cacheu became well-known as a major center for the practice.
Portuguese settlers controlled the area for centuries, until 1956 when Amilcar Cabral and Rafael Barbosa secretly organized the African Party for the Independence of Guinea and Cape Verde (PAIGC) and staged an armed rebellion against the Portuguese in 1961.
Independence wasn't achieved until 1974, following the Carnation Revolution (a military coup in Lisbon, Portugal).
Upon independence, the name of its capital, Bissau, was added to the country's name to prevent confusion with the Republic of Guinea.
Since their independence from Portugal, Guinea-Bissau has experienced considerable political and military upheaval. In 1980, a military coup established authoritarian dictator Joao Bernardo 'Nino' Vieira as president. Despite setting a path to a market economy and multiparty system, Vieira's regime was characterized by the suppression of political opposition.
Several coup attempts through the 1980's and early 1990's failed to unseat him. In 1994, Vieira was elected president in the country's first free elections. A military mutiny and resulting civil war in 1998 eventually led to Vierira's ouster in May 1999. In February 2000, a transitional government turned over power to opposition leader Kumba Yala, after he was elected president in transparent polling.
In September 2003, after only three years in office, Yala was ousted by the military in a bloodless coup, and businessman Henrique Rosa was sworn in as interim president. In 2005, former President Vieira was re-elected president pledging to pursue economic development and national reconciliation.
Vieira, who described himself as "God's gift" to Guinea-Bissau, was killed by soldiers in March, 2009. He's the only president of Guinea-Bissau to be assassinated. Malam Bacai Sanhá was elected the new president in elections in June, 2009.
Guinea-Bissau's GPD per capita and its Human Development Index are two of the lowest in the world. Over 2/3 of its population live below the poverty level – all caused by political instability.
Cacheu fortress, Guinea-Bissau Nammarci at en.wikipedia
A busy street in Guinea-Bissau