Jean might see that people in China look different and there is different cultural exercises. I think it would be the same if someone were to go from France to China, but there is more diversity among the world, so we could see people from China, Asia, Africa, Mexico and more. So its more common.
And they might call Jean a foreign devil because they are going to another country and leaving their own country.
His point of view is thinking of Jean as a traitor for leaving his country, but Jean might just be trying to learn form others and explore.
Hope this helps!!