Standard Cantonese has six tones, Minnan, spoken primarily in Taiwan and Fujian, has five to seven; and so on down to Mandarin, based on the Beijing dialect, which has only four. (I don't count neutral "tone", as it is conditioned by its environment).
Are there any dialects that have fewer than four? Examples of pronunciation would be very helpful, as would any references in the scholarly literature.
Sorry! In asking the question I should have considered the difference between "phonetic" tones and "phonemic" tones. Different analyses can come up with different tone inventories and different numbers of tones. Thanks for the clarifying comment below.