Where did assassin Wu's accent come from?

Before 567 lost his memory, he was the chief shadow assassin of Xuanwu Assassin League. He speaks standard Cantonese, which is called Cantonese in Guangdong and Cantonese in Guangxi. He is a kind of tonal language, belonging to the Sino-Tibetan Chinese dialect. I want to speak Cantonese, because I can hear from what he said that he is definitely not Mandarin, and his accent is very similar to Cantonese.