 Despite their renewed dominance, the Incas failed however to conquer the nomadic tribes in the eastern Bolivian lowlands.The remains of Incan fortresses here reveal evidence of this failure and suggest that Incas could subdue only those cultures based on agricultural activities.As a result of their resistance, the nomadic tribes in the eastern lowlands occupying two-thirds of Bolivia preserved their way of life to a great extent, even after the Spanish conquest.