South of the Norrland terrain lies the Central Swedish lowland which forms a broad east-west trending belt from Gothenburg to Stockholm. This is the traditional heartland of Sweden due to its large population and agricultural resources. The region forms a belt of fertile soils suitable for agriculture that interrupts the forested and till-coated lands to the north and south. Before the expansion of agriculture, these fertile soils were covered by a broad-leaved tree forest where maples, oaks, ashes, small-leaved lime and common hazel grew. The Central Swedish lowland does however also contain soils of poor quality, particularly in hills where Scots pine and Norway spruce grow on top of thin till soils. Agriculture aside, the region benefits also from the proximity of hydropower, forest and bergslagen's mineral resources. Sweden's four largest lakes, Vänern, Vättern, Mälaren and Hjälmaren, lie within the lowlands.