Mr. George works at the school lost and found. He works very carefully. Every day, when he gets a lost thing, he takes notes about it. There are pens, books, school uniforms, keys, walkmans and many other things in the lost and found. Most of them are the students’. If you lose your things, it’s easy for you to go to the lost and found for help. But you must tell Mr. George what it is and its color and the day when you can’t find it. I think Mr. George is very helpful, and you will be happy when you find the lost there.

“外甥是先皇帝舅宿亲，又蒙降金城公主，遂和同为一家。天下百姓，普皆安乐。”这段话体现了中国古代哪两个民族之前的友好关系（  ）