The region was an important Swahili trade center before the Portuguese colonial era. On the east coast of Africa the Portuguese were drawn to Mozambique and the Zambezi river by news of a local ruler, the Munhumutapa, who was said to have had fabulous wealth in gold. In their efforts to reach the Munhumutapa, the Portuguese established in 1531 two settlements far up the Zambezi – one of them, at Tete, some from the sea. The Munhumutapa Kingdom and gold mines remained autonomous and mostly isolated from the Portuguese. But in this region of east Africa – as in Portuguese Guinea and Angola in the west – Portuguese involvement became sufficiently strong to survive into the third quarter of the 20th century. Under Portuguese influence Tete had become a market centre for ivory and gold by the mid-17th century. Given a Portuguese town charter in 1761, it became a city of the Portuguese Overseas Province of Mozambique in 1959. After the Portuguese Colonial War in Portuguese Africa and the April 1974 military coup in Lisbon, the then Portuguese Overseas Province of Mozambique become an independent state. The newly independent People's Republic of Mozambique, created in 1975 after the exodus of Mozambique's ethnic Portuguese, descended into civil war between 1977 and 1992.