Western Finland was influenced by baking and cultivation techniques from Scandinavia, whereas eastern Finland was exposed to Russian influences. In North Karelia, in eastern Finland, households baked their bread in large ovens several times a week and the bread was eaten fresh. Bread was made from rye and dough heart (sourdough starter) could be hundreds of years’ old, bread raised without added yeast. In western Finland, it was not as common for bread to be baked weekly. Baking happened probably once or twice a month using barley and oats. Added yeast was used in the dough. Before baking, a small hole was made in the corner of the round, flattened bread, and after baking the bread was hung on poles suspended just below the kitchen ceiling to dry and for storage: see ruisreikäleipä. Barley, and sometimes wheat, was used in the western part of Finland. The most frequently cultivated grain was rye, followed by barley. Bread culture in central Finland was influenced by both the East and the West. Bread was also influenced to some extent by Lapland; bread was called “rieska”, but it was much thicker than Lappish rieska. Lapland was strongly influenced by both Swedish Lapland and Norway. The most varied bread traditions in Finland are to be found in the regions of Karelia and Kainuu, where cereals have been ingeniously combined with other natural products such as berries, fish and vegetables. Rice is a traditional filling in the Karelian pastry and the latest research show that this influence has a Russian origin, where rice was used in pastries as early as the 17th century. In the 19th century, bread-making in the cities moved to local bakeries. Poor households baked their own bread daily in small apartments. The bread consisted of thinner, multigrain breads, elongated "sekaleipä" mixed-cereal bread. Bread was made from all four of the cereals grown in Finland: wheat, rye, barley and oats, usually ground into various grades. Rye bread can be either light or dark in colour, depending on the type of flour mixture used, and it is typical for rye bread to include about 20% wheat flour. New trends and old traditions are bringing old-fashioned rye breads back to the shelves in shops. These rye breads are made entirely from rye flour and are the most common breads in the Finnish diet. Other types of sour bread are still baked in the residual heat of ovens and the longer baking time at low temperature gives the bread both a darker colour and a higher density and hardness than ordinary rye bread.