Complex sentence: John McLoughlin, the director of the Columbia operations of the Hudson's Bay Company at Fort Vancouver on the Columbia River, heard of Bonneville's mission and forbade his traders from doing business with Bonneville and his men.
Split into simpler sentences: John McLoughlin, the director of the Columbia operations of the Hudson's Bay Company at Fort Vancouver on the Columbia River, heard of Bonneville's mission. He forbade his traders from doing business with Bonneville and his men.