Whose ancestors migrated from the Central Plains? Hakka? Chaoshan people?

Just searched it. Chaozhou people has two nicknames: one is Lao Luo, which means that chaozhou people's ancestors immigrated from Luoyang, Henan. There is another nickname: "Fu Lao", which means that people from the ancient Central Plains immigrated to Fujian, and some moved from Fujian to Chaoshan area. Chaozhou dialect, like Minnan dialect, belongs to Fujian language family. I don't know what a Hakka is yet.