Complex sentence: One went by boat along rivers and overland to the Yukon River system at Pelly River and from there to Dawson.ther went north of Dawson by the Mackenzie River to Fort McPherson, before entering Alaska and meeting the Yukon River at Fort Yukon, downstream to the Klondike.
Split into simpler sentences: One went by boat along rivers and overland to the Yukon River system at Pelly River and from there to Dawson. Another went north of Dawson by the Mackenzie River to Fort McPherson, before entering Alaska and meeting the Yukon River at Fort Yukon, downstream to the Klondike.