Complex sentence: This new area of economic activity, not brought great profits to the company, but also benefitted Criollos with large landholdings, who developed plantations on their properties, but did not help small-time farmers, who continued to participate in the southern contraband trade.
Split into simpler sentences: This new area of economic activity, not brought great profits to the company, but also benefitted Criollos with large landholdings, who developed plantations on their properties. However, it did not help small-time farmers, who continued to participate in the southern contraband trade.