Naxi, being a tonal language, has four main tones.
1) the mid level tone - pa˧ (33)
2) the high level tone (similar to the first tone in mandarin) - pa˥ (55)
3) the low rising tone (similar to the second tone in mandarin) - pa˩˧ (24)
4) the falling tone (similar to the fourth tone in mandarin) - pa˧˩ (21)
Alexis Michaud, of the University of Paris, has done a lot of work on tones in Naxi and you can visit his homepage here, from which you can find links to some of his articles available to download. These treat the subject in a lot more depth than I could ever hope to.