The expulsion of the Dutch demonstrated the toughness of the early Brazilians, which was also well to the fore in the penetration and settling of the interior during the seventeenth and eighteenth centuries. Every few months, expeditions set out to explore the interior, following rumours of gold and looking for Indians to enslave. They carried an identifying banner, a bandeira, which gave the name bandeirantes to the adventurers; they became the Brazilian version of the Spanish conquistadores. São Paulo, thanks to its position on the Rio Tietê, one of the few natural highways that flowed east-west into the deep interior, became the main bandeirante centre.

The average bandeira would be made up of a mixed crew of people, reflecting the many - and often conflicting - motives underlying the expedition. None travelled without a priest or two ( bandeirantes may have been cut-throats, but they were devout Catholic cut-throats), and many bandeiras were backed by the Jesuits and Franciscans in their drive to found missions and baptize the heathen. The majority combined exploration with plundering and could last for years, with occasional stops to plant and harvest crops, before returning to São Paulo - if they ever did: many towns on the Planalto Central or Mato Grosso have their origins in the remnants of a bandeira. The bandeirantes had to fight Indians, occasionally the Spanish, and also themselves: they were riven with tension between native-born Brazilians and Portuguese, which regularly erupted into fighting.

The journeys bandeiras made were often epic in scale, covering immense distances and overcoming natural obstacles as formidable as the many hostile Indian tribes they encountered, who were defeated more by diseases to which they had no resistance, than by force of arms. It was the bandeirantes who pushed the borders of Brazil way inland, practically to the foothills of the Andes, and also supplied the geographical knowledge that now began to fill in the blanks on the maps. They explored the Amazon, Paraná and Uruguai river systems, but the most important way they shaped the future of Brazil was in locating the Holy Grail of the New World: gold.

Gold was first found by bandeirantes in 1695, at the spot that is now Sabará, in Minas Gerais. As towns sprang up around further gold strikes in Minas, gold was also discovered around Cuiabá, in Mato Grosso, in 1719, adding fresh impetus to the opening-up of the interior. The 3500-kilometre journey to Cuiabá, down five separate river systems, took six months at the best of times; from São Paulo it was easier to travel to Europe. Along the way the bandeirantes had to fight off the Paiaguá Indians, who attacked in canoes and swam like fish, and then the Guaicuru, who had taken to the horse with the same enthusiasm the Plains Indians of North America were later to show. They annihilated entire bandeiras; others following left descriptions of "rotting belongings and dead bodies on the riverbanks, and hammocks slung with their owners in them, dead. Not a single person reached Cuiabá that year."

But the Paulista hunger for riches was equal even to these appalling difficulties. By the mid-eighteenth century, the flow of gold from Brazil was keeping the Portuguese Crown afloat, temporarily halting its long slide down the league table of European powers. In Brazil, the rush of migrants to the gold areas changed the regional balance, as the new interior communities drew population away from the Northeast. The gateways to the interior, Rio de Janeiro and São Paulo, grew rapidly. The shift was recognized in 1763, when the capital was transferred from Salvador to Rio, and that filthy, disease-ridden port began its transformation into one of the great cities of the world