The oldest tradition stopped before it got back to him.

From the beginning there had been an ancient and ramshackle cabin.

Dying men had sworn to it, and to the mine the site of which it marked, clinching their testimony with nuggets that were unlike any known grade of gold in the Northland.
But no living man had looted this treasure house, and the dead were dead; wherefore John Thornton and Pete and Hans, with Buck and half a dozen other dogs, faced into the East on an unknown trail to achieve where men and dogs as good as themselves had failed.

They sledded seventy miles up the Yukon, swung to the left into the Stewart River, passed the Mayo and the McQuestion, and held on until the Stewart itself became a streamlet, threading the upstanding peaks which marked the backbone of the continent.
John Thornton asked little of man or nature.

He was unafraid of the wild.