The Haka is a traditional Maori dance
This is a special version of the Haka called Kapa o pango - reserved for big games
The haka was traditionally performed before charging into battle
The first Haka was performed by a New Zealand rugby team in Britain in 1888
The All Blacks Haka involves loud chanting, aggressive body movements & fierce facial expressions; it's seen as a challenge thrown down by the All Blacks to their opponents on the field

Gives bit of an idea what the 'red coats' would have been faced with in the 19th century