The two main Chinese sources for the conquest of Greek Bactria are chapter 123 of the Shi-ki of Ssu-ma Ch'ien, who is said by Hirth to have finished his history about 99 b.c. (some put it rather later) and who reproduces Chang-k'ien's Report, more or less interwoven with his own narrative but in places apparently given verbatim; and chapters 96 (both parts) and 61 fols. 1-6 of the Ch'ien-han-shu (Annals of the Former Han) of Pan-ku, who died in a.d. 92 and whose history, left incomplete at his death and finished by his sister, runs from 206 b.c. to a.d. 24; chapter 61 fols. 1–6 contains among other things a Life of Chang-k'ien, largely drawn from himself, and chapter 96 is Pan-ku's own account of the Western Countries, based on Chang-k'ien's Report which is sometimes apparently quoted verbatim, but incorporating later material. Ssu-ma Ch'ien is supposed to be the more valuable source for what Chang-k'ien actually wrote, but it is not always easy to say what is Chang-k'ien and what is Ssu-ma Ch'ien; the latter writer brings in later material just as Pan-ku does, and for historical purposes chapter 123 of the Shi-ki requires the same kind of critical analysis as has been applied to many Greek historians; I have done what little I can from a translation (see for example p. 281) but I do not pretend that it can be satisfactory. Pan-ku (who of course needs a similar analysis) had much new information at his disposal which Ssu-ma Ch'ien had not possessed, and his occasional corrections of the latter on matters like geography can be valuable.