Meanwhile, Garay was clinching his claim to immortality as the founder of the Spanish power on the Plate. He explored the pampas to the south and west of the new city, and reduced many of the tribes to slavery or vassalage. He found the plains already overrun with hundreds of thousands of horses--the descendants of the few abandoned there forty-five years before when the remnants of Mendoza's ill-starred expedition fled up the river. On his way back to Santa Fe this great Indian fighter was ambushed by Indians and stabbed while he slept. His death was followed by outbreaks among the creoles, who resented the efforts of the adelantado's new representatives to establish a monopoly in horse-hair. Scarcely had they found a way to make a little money, by hunting wild horses for their hair, than the officials tried to absorb all the profit. The struggle between the repressive commercial policy of Spain, and the interests of the Plate colonists, began with the foundation of the colony of Buenos Aires and went on for more than two hundred years. In 1588, the creoles obtained a foothold in the extreme north of the mesopotamian region by founding the city of Corrientes near the junction of the Parana and Paraguay. All the new commonwealths south of Asuncion obtained a solid economic foundation in the herds of cattle and horses which covered the plains. In the regions adjacent to the Andes the Spaniards did not become so exclusively pastoral as their brethren of the pampas near the Plate. While they had more and better Indian slaves, their pasturage was not so good. Though apparently more isolated, their proximity to Upper Peru and the trade that went on with that great mining country--the goal of fortune-hunting Spaniards in those years--placed them more directly under the control of the viceregal authorities. Tucuman was a mere southern extension of the jurisdiction of the Audiencia at Charcas, and Cuyo was an integral part of Chile, but this did not prevent the early development of a strong sentiment in favour of local self-government and of hatred of the imported Spanish satraps. By the year 1617 the settlements on the Lower Parana had become of considerable importance. Buenos Aires was a town of three thousand people; the right bank of the river as far as Santa Fe was a grazing-ground for the herds of the creoles; towns and ranches were flourishing in Corrientes. In that year the Spanish crown abolished the office of adelantado and erected the lower settlements into a province separate from Paraguay. The new province included the territory that is now Uruguay, as well as the four actual Argentine provinces of Buenos Aires, Santa Fe, Entre Rios and Corrientes. Entre Rios and Uruguay were, however, as yet entirely unsettled.