sentences:  The northern route started in Fort McPherson, Northwest Territories along the Mackenzie River, crossed the mountains into the Bell and Porcupine Rivers to the Yukon River.The southern route started at Fort Liard, Northwest Territories, then westward along the Liard River to Frances Lake and then along the Pelly River to its juncture with Yukon River.After establishing Fort McPherson, Northwest Territories, John Bell crossed the mountains into Yukon River watershed in 1845, and went down the Rat River (today the Bell River) to its confluence with the Porcupine River.