But of all the markets of the merchants of Dubrovnik, those which from the days of old they most frequented, were the markets of the Balkans. To Bulgaria and Serbia, Albania and Bosnia, they brought the products of the West and of their own factories: the cloth and metal goods, the silver and gold ornaments, the weapons, axes, harness, glass, soap, perfumes, southern fruits, fish oil and herbs; and most of all they valued their monopoly of salt, a most remunerative privilege. As they could not obtain sufficient of it in their own immediate territory, the Senate made a regulation that each vessel which came back after a voyage of four years must bring a cargo of salt. This was Dubrovnik's chief source of revenue until the end of her independence in 1808, and efforts that were made by others to break down this monopoly led to bitter conflicts. With regard to the goods which they carried home with them from the Balkans, these comprised cattle and cheese, dried fish from the Lake of Scutari, hides of the wolf and fox and stag, wax, honey, wool and rough wood-wares, and unworked metals. Some of the Balkan mines, such as the silver mines of Novo Brdo in Serbia, they worked themselves, even as the Saxons whom we find thus engaged in various parts of these lands. Under the Turkish domination it must have been with joy that the caravans from Dubrovnik were welcomed, bringing news of the one Southern Slav State which remained free and prosperous. A good many of these wandering merchants took Serbian or Bulgarian wives. HER COMMERCIAL ENTERPRISE If the men from Dubrovnik were able to bring happy tidings of their own Republic, such as the report, perhaps a little exaggerated, that the wealth of those who lived in the street of merchants, which runs parallel to the stately thoroughfare, the Stradone, amounted to a hundred million ducats, they were able to give very little news of the more distant Southern Slavs. The Serbs had not forgotten that brothers of theirs were living in the north-west. If in the days of the Turkish oppression they had been inclined to be oblivious of the Croats, yet they could not but remember that Dušan's sister had married the Croatian prince, Mladen III. There is no incident connected with Dušan that is not treasured in the memory of the Serbs. HER NORTHERN KINSMEN AND THE MILITARY FRONTIERS