Many Indians were forced to abandon their tribes to work on the farms .
The frontier dividing the colonial farms and the Indian territories gradually moved outwards from Buenos Aires ; at the end of the 18th century , the Salado River was the boundary between the civilizations .
Many Indian were forced to abandon Indian 's tribes to work on the farms .
The frontier dividing the colonial farms and the Indian territories gradually moved outwards from Buenos Aires ; at the end of the 18th century , the Salado River was the boundary between the civilizations .