Ancient Chinese pronunciation is closer to Cantonese than
Mandarin. Mandarin is a mix of Barbarian languages because North
China was conquered many times by barbarians.
So the ancient Tang poems of Li Pai and Tu Fu are actually more
suited to Cantonese, being closer to the ancient Chinese.
After the Manchus fell in 1911, modern China wanted to choose a
National Language. Some wanted Cantonese, others wanted
Mandarin.
Had cantonese became the National language, we would all be
speaking Cantonese and not some foreign Beijing dialect called
Mandarin.
Um Koi Sai
(thank you)