The culture of the Viking Age was strong, independent, rich in tradition and vibrant. It was good at copying, adapting, developing and creating; foreign ideas could be incorporated or rejected. The lands of Viking Age Scandinavia, apart from Finland and the Sami areas in their northern and central parts, shared a substantially common culture. The varied natural resources of Scandinavia encouraged shipping and trade; thus shipping was a decisive factor in the more general expansion and common culture of the period. Other communication routes, using sledges, skis, snowshoes or skates, developed where there was a stable snow and ice cover for several months of the year. Agriculture in various forms was the predominant economic activity. But with the growth of trade, the Viking Age saw the emergence of town-like settlements in Scandinavia, and trade and crafts became increasingly specialist occupations. The religion of the Viking Age was polytheistic. A multitude of gods and powers influenced the different aspects of life.