Complex sentence: Around 1910,56.8% of the region's land mass was cultivated and 38% was forested, but the agricultural sector, which before 1870 yielded the bulk of the region's wealth, had been superseded by industrial production.
Split into simpler sentences: Around 1910,56.8% of the region's land mass was cultivated and 38% was forested. Before 1870, the agricultural sector, was responsible for the bulk of the region's wealth, but this was superseded by industrial production.