Not really sworn enemies, but there's a cultural and ethnic divide, exacerbated by the fact that a Mancurian dynasty ruled over the Han Chinese for some centuries.
No! Please call me by my name!Eh!? Why!?The EndLet me introduce her. This is Manchuria.Let's go Manchuria.What theAnd she's better at cooking than you?We've hired someone new who's more useful than you.ChinaNice to meet you!This is sudden, but you're fired.