There are some strange claims on that site. There are no sources listed, so I'd assume it's because none were used.
"We could define tribal bellydance as all dances that are indeed tribal and form in one way or another a source of inspiration to oriental dance and modern tribal style dancing in particular."
?????WTF?????
"What is common that it is not a solo dance but a troupe or tribe dance, the cues and transitions system makes the improv dance a chain of sisters."
I thought synchronized dance groups were origianally a Western European concept?
Synchronized sisters dancing as a tribe using cues and transitions: