The connecting link between the western and the eastern Baltic was the isle of Gotland, where German merchants from Lubeck had established a depot (the later Visby)_ The fur-trade with the Esthonians and Livonians proved so lucrative that a German colony was planted in Livonia itself at what was afterwards Riga, and in 1201 for its better security the colony was converted into a bishopric. A still firmer footing was gained by the Germans on Livonian soil when Abbot Theoderick of Riga founded the order of the Sword (a foundation confirmed by the pope in 1204), whose duty it was to convert the heathen Esths and Livs and appropriate as much of their land in the process as possible.
Traders had begun to swarm into the country in increasing numbers, and to protect them from the Indians and to control properly the licensed fur-trade a military force was necessary.
In this period, however, the fur-trade assumed proportions of greater importance, and trading posts were established by the North-west Company (Canadian).
Until 1830 the fur-trade, controlled largely by John Jacob Astor's American Fur Company, continued to be the predominating interest in the Wisconsin region, but then the growing lead mining industry began to overshadow the fur-trade, and in the mining region towns and smelting furnaces were rapidly built.
In many of these fur-trade enterprises, kinship ties proved far more enduring than company loyalties.