Belarusian culture is the product of a millennium of development under the impact of a number of various factors. These include the physical environment; the ethnographic background of Belarusians; the paganism of the early settlers and their hosts; Byzantine Christianity as a link to the Orthodox religion and its literary tradition; the nation's deficiency of natural borders; the flow of rivers toward both the black Sea and the Baltic Sea; and the mixture of religions in the region; Catholicism, Judaism, and Islam. An early Western determine on Belarusian culture was Magdeburg Law--charters that granted municipal self-rule and were based on the laws of German cities. These charters were granted in the 14th and 15th centuries by grand dukes and kings to a number of cities, including Brest, Hrodna, Slutsk, and Minsk. The tradition of self-government not only facilitated contacts with Western Europe but also nurtured self-reliance, entrepreneurship, and a sense of civic responsibility. In 1517-19 Frantsishak Skaryna translated the Bible into the vernacular. Under the communist regime, Skaryna's work was hugely undervalued, but in independent Belarus he became an inspiration for the emerging national consciousness as much for his advocacy of the Belorussian language as for his humanistic ideas. During the 17th and 18th centuries, when Poland and Russia were making deep political and cultural inroads in Belorussia by assimilating the nobility into their respective cultures, the rulers succeeded in associating "Belorussian" culture primarily with peasant ways, folklore, ethnic dress, and ethnic customs, with an overlay of Christianity. This was the point of departure for some national activists who attempted to attain statehood for their nation in the late nineteenth and early twentieth centuries. The development of Belorussian literature, spreading the idea of nationhood for the Belorussians, was epitomized by the literary works of Yanka Kupala and Yakub Kolas. The works of these poets, along with several other outstanding writers, became the classics of modern Belorussian literature by writing widely on rural themes and by modernizing the Belorussian literary language, which had been little used since the sixteenth century. Postfreedom authors in the 1990s continued to use rural themes widely.