 He also enacted measures against smuggling caused by prohibitions on import, export and the African slave trade.During his term as governor of Buenos Aires, Hernandarias started several expeditions, including ones to Uruguay and Brazil to rein in the Portuguese "bandeirantes", explore the Patagonia, survey the navigability of rivers and to find the mythical "City of the Caesars".Eventually in 1604, he was captured by the native Mapuche around 1,000 km south of Buenos Aires.