Sinitic and Tibetic

"I believe that it is time for Sinologists to take a cue from the Tibetologists. Out of a total population of more than 1.3 billion in the People's Republic of China, there are supposedly almost 1.2 billion speakers of "Chinese." This is held to be a single "language," not a "family," "branch," or "group" of languages, but a monumental, monolithic LANGUAGE consisting of multitudinous "dialects." Since many of these so-called "dialects" are mutually unintelligible, language taxonomists fudge a bit by calling some of them "major dialects," "sub-dialects," and so forth. However, several of the "major dialects" — all of which are mutually unintelligible — have upwards of 20 million speakers: Mandarin (c. 850 million), Wu (nearly 100 million), Cantonese or Yue (around 90 million), Min (over 50 million), Xiang and Hakka (approximately 35 million each), Gan (roughly 20 million), and Jin ([a disputed subdivision of Mandarin] about 45 million). Moreover, many of these huge "major dialects" comprise scores of "dialects" that have a very low degree of mutual intelligibility (or none at all) and a highly complex set of internal relationships. For example, Min is divided into Eastern Min, Southern Min, Central Min, and so forth, and these branches are further subdivided into varieties that are quite different among themselves. For instance, Southern Min is made up of Quanzhou, Zhangzhou, Amoy (Xiamen), Teochew (Chaozhou), Leizhou, and Hainanese, all of which are significantly dissimilar."

http://languagelog.ldc.upenn.edu/nll/?p=2219