The banker had negative feelings towards the jurist. In the story, the jurist did him some not so good things. We would expect that the wager was done out of hatred for the jurist. The banker wanted to take revenge aginst the jurist.
China.
The Silk Road is a trading route from the Middle East to China, and the ancient civilizaitons practiced ancestor worship. The Mandate of Heaven dictates that good weather and general prosperity are because of divine approval of the leader of China. If there is famine, invasion, or other natural disasters, it was interpreted as needing a new ruler, aka losing the mandate of heaven.
