what is now eastern Finnmark. Finally, Vardøhus Fortress was constructed to mark and defend the border with the Karelian tributary lands of the Novgorod Republic. The traditional view has been that the fortress and church were constructed at roughly the same time, although recent research indicates that the fortress may have been constructed as late as the 1330s, after the border between Norway and Novgorod had become more fixed. At roughly the same time, the cod fishing gained momentum. Dried cod was exported through Bergen to the whole Hanseatic world, bringing prosperity to the north. This is reflected in the numerous pieces of imported church art from the Late Middle Ages. There were numerous wars with the Novgorod Republic in Russia at the time, that stopped by the late 15th century. Reduced fish prices in the 17th century and the exploitative trade practices of merchants from Bergen, who had been granted a royal monopoly on fish trading, led to a significant decline in the population and grinding poverty for those who remained. Large coastal areas were depopulated, and Sami culture made a comeback, as it was less dependent on fish exports. After 1700, Russian Pomors started to come every summer on trading expeditions, bringing rye in exchange for fish. Although this was in violation of Bergen's trade monopoly and the Danish–Norwegian monarchy made some attempts to curtail the Pomor trade, the trade was vital to the survival of many Northern Norwegian fishing communities. In the 1740s the first settlers started arriving in Northern Norway from Finland. The traditional view is that these were refugees escaping famine and warfare at home, although modern scholars have pointed out that many were simply looking for their own piece of land, which was getting scarce in Finland as a result of rapid population growth. In 1789, the trade monopoly of the city of Bergen was lifted, Hammerfest and Vardø were issued their city charters, and Tromsø followed suit in 1794. Interrupted by the British blockade of the Napoleonic wars, this introduced a period of unprecedented growth in the north as the trade monopoly had previously made cities nonviable in Northern Norway. Bodø was founded in 1816, and Vadsø in 1833. The Hurtigruten shipping line, introduced in 1893, gave quicker communications with the south. In 1906, the iron mines in Kirkenes opened. At the same time, the ethnic diversity of the area came under threat.