In many branches of Ural-Altayic, investigations are far from being exhaustive. This is particularly true of the Tungus group, inasmuch as with the exception of one sub-division—Mandžu—little research has been done. So far even the classification of the Tungus languages and dialects remains a subject for controversy. In the standard work on Tungus ethnology, Social Organization of the Northern Tungus (Shanghai, 1929), by S. M. Širokogorov, the languages are divided, in accordance with the author's hypothesis concerning Tungus migrations, into a northern and a southern group. The southern group includes Mandžu, the historical language of the Ňu-Čžen (also: Jučen and Džürdžen), Goldi, and Olča (lower Amur). The remaining Tungus languages are placed in the northern group, which today is called Eveŋki (‘the people‘), a term used by the Tungus themselves. Širokogorov, as well as other scholars, disregards a third Tungus group, the Even or Lamut. These consist of hunters and reindeer-breeders who roam in scattered groups over the vast territory between the Khatanga river (100° E. long.) and the Anadyŕ (165° E. long), infringing on the territory of the Jakut in the lowlands of the Lena, Jana, and Indigirka rivers. They are thus separated from their southern kinsmen, the Eveŋki, by a distance of nearly 1300 miles. The geographic distribution of the Tungus cannot be here discussed in detail. Eastward of the ninetieth meridian almost two-thirds of the entire Siberian territory are inhabited by the Tungus.