After the delay of some months in his new settlement, Ayolas determined to find his way in the direction of _Peru_; and taking with him a sufficient party, he left one of his officers, Irala, with fifty Spaniards, at _Candelaria_ on the _Paraguay_, as a supporting party in case of his retreat. The succeeding months were occupied by him in wanderings in the primeval forest, where he received from a tribe the glad tidings of the presence of gold and silver in the adjacent regions. Ayolas and his party were, however, compelled to find their way back, when they were doomed to disappointment in not meeting Irala, who, despairing of their return, after waiting six months, had returned to _Asuncion_. Ayolas and his people were soon after murdered by the tribe of _Payaguas_. Irala meanwhile, having repaired his vessels, returned to _Candelaria_ and made fresh, but of course fruitless efforts to discover Ayolas, whose death, when he had ascertained it, he cruelly avenged on some _Payaguas_.
Learning the tale of treasure to be found in the interior, Irala now bent his attention to discover it. At _Buenos Ayres_ wealth could only be the reward of industry, and therefore the settlement founded by Mendoza was abandoned, and the whole Spanish colony flocked up the river to _Asuncion_. They mustered six hundred souls, and _Asuncion_ thus became the earliest founded permanent city in the region of _La Plata_.
It being believed in Spain, before the fact was ascertained, that Ayolas was dead, the post of _Adelantado_ of _La Plata_ was conferred upon _Don_ Alvar Cabeza de Vaca, who had passed ten years as a prisoner amongst the natives of _Florida_. Cabeza de Vaca sailed from Spain with four hundred followers in the year 1540, and by the following March had disembarked at _Santa Catalina_, an island on the coast of _Brazil_, opposite _Paraguay_, where confirmation reached him of the death of Ayolas. He thereupon boldly proceeded from a point of the shore near to _Santa Catalina_, making direct by land for _Asuncion_. He took with him two hundred and fifty men with twenty-six horses, sending the remainder by water to _Buenos Ayres_. During nineteen days Cabeza marched through woods ere reaching a settlement of _Guaranís_, from whom he was enabled to obtain abundance of food for his men.