The first Jesuit reduction to Christianize the indigenous population was founded in 1609, but some areas occupied by Brazilians as bandeirantes gradually extended their activities through much of the basin and adjoining Mato Grosso in the 17th and 18th centuries. These groups had the advantage of remote geography and river access from the mouth of the Amazon, which was in Portuguese territory. Meanwhile, the Spanish were barred by their laws from enslaving indigenous people, leaving them without a commercial interest deep in the interior of the basin.