A 69-page welcome booklet printed in June 2018 contained the phrase, as highlighted by Indian-American comedian Hasan Minhaj.
"If you are sent on a training mission in Saudi Arabia, this is the official military document you get," Minhaj said on his show "Patriot Act," which premiered Sunday on Netflix. "Oh, America, even in boring technical manuals you somehow manage to be racist."
"The population of [Saudi Arabia] is mainly composed of descendants of indigenous tribes that have inhabited the peninsula since prehistoric times with some later mixture of Negro blood from slaves imported from Africa," says a section titled "People and Population," according to Stars and Stripes.
The booklet contains a lot of useful information about Saudi cultural practices different from those in Western countries with which US personnel might be more familiar, such as a lack of pornography and alcohol, the differences between Sunni and Shia Islam and the numerous prohibitions on receiving shipments through military mail.
However, in addition to the race science language, there are also bizarre and sweeping generalizations such as: "To speak of the Saudi Arab is to speak of his religion and culture, for they are bound together inextricably," Vox noted.
CENTCOM has since removed the publication from its website and offered an apology for the language.
"We regret that inappropriate material was posted to our website without a more fulsome review and apologize to anyone who took offense," CENTCOM spokesperson Capt. Bill Urban said in a statement Friday. "We removed the document as soon as we were notified of the content, and it was returned to the originating office for revision."
Vox noted that, in all likelihood, the language was inherited from earlier iterations of the document that escaped the attention of copywriters who probably don't revise each document every time it's reprinted. However, none of the at least 140 advisers given the document after it was printed seem to have said anything, either, the publication notes.