In current academic circles, the description 黑色 "Black" found in 《居延汉简》has been commonly taken as the color of one's skin tone. For instance, 《居延汉简》: “长安有利里，宋买，廿四，长七尺二寸，黑色” 《居延汉简》:"槖佗延壽長孫時符, 妻大女昭武萬歲裏孫弟卿年廿一, 子小女玉女, 年三歲, 弟小女耳, 年九歲, 皆黑色." 《居延汉简》: "都里不更司馬奉德, 年廿, 長七尺二寸, 黑色." I, however, am not convinced for the following reasons: 1) If 黑色 indeed represents one's complexion, why didn't 《居延汉简》 also record other exotic skin colors (e.g., "white")? Why did Chinese single out the Blacks? Were Chinese "blind" to "white"--I mean the so-called "white" complexion was not a concept in Chinese minds then or the Whites were not considered "exotic" then so that it was not worth mentioning in their 户籍? 2) 槖佗延壽's ancestors were probably Tocharian (月氏人) based on the surname 槖佗‘camel’ although he could be a 匈奴 subject (Note: Xiongnu 槖佗 *thaktha and later Uighur toga ‘camel’ were borrowed from Tocharian -tākto) . It is unlikely that 匈奴人with a 月氏 ancestry would have a "black" skin tone. 3) 黑色 strikes me as an unusual expression. The more idiomatic ways for me would be "黑人", "皆黑人", "肤黑", "皆肤黑","黑肤", "黑种", "皆黑种" and so on. Then again, if 黑色 did not mean the skin color, what could it mean?