The territory ruled by a duke or duchess; a dukedom.

由大公或女大公统治的领土。

This is, after all, a modern government, not a medieval dukedom.

毕竟，如今是一个现代的社会，而不是中世纪的王国。

And within a dukedom, the struggle for power frequently occurred.

而且，在一个公国内部，权力之争也时常发生。

The old man said, "the duke of Chen is trusted by the king and his dukedom has good relationship with ours."

老人说：“陈国公爵受到周天子的信任，而且陈国和我国关系很好。”