The Jesuits were concerned that city of Asuncion would soon fall to the Mamelucos. Their lives and the lives of the Indians lay in a perilous dilemma. The Mamelucos and the reduction armies meet in 1641 at the Uruguay River. Soon, the Mamelucos armies were being destroyed and by March of that year the reductions army had claimed victory. The banderiantes were defeated and in 1640 Portugal retained its independence under the crown of Spain. With the reduction army's victory and Portugal reconstituted, the slave threat became less of a worry. For now the threat of the Mamelucos and Paulistas was now in check. .
By 1700 the Jesuits could again count one hundred thousand inhabitants in over about thirty reductions. This period was a time of the most drastic expansion for the Jesuits. From 1641 to 1706 the reductions were very profitable and exported cotton linen cloth, hides, tobacco, lumber and above all yerba mate. Yerba mate was a plant that was used to produce a bitter tea and to this day is very popular in Paraguay and Argentina. They Jesuits also raised food crops and taught arts and crafts. In addition, they were able to render considerable service to the crown by supplying Indians for use against the Portuguese, English and French. At the time of the expulsion of the Jesuits from the Spanish Empire in 1767, the reductions were enormously wealthy and compromised more than twenty one thousand families. The Gurnai women were almost much sought after, "Like the colonists of the cost of Brazil, the settlers at Asuncion were strongly attracted by the fine features of the Gurani women and readily took them as wives". One early writer noted: "the women generally re virtuous, beautiful and of a gentle disposition". "The marriages made for peace, particularly when the bride was the daughter of a cacique. With their strong sense of family, the Indians felt obliged to assist or at least not to molest their newly acquired relatives.