This question was asked in some previous threads (one, two), but I found none with answers.
If an answer within China is not available, information for elsewhere in Asia would also be useful.
I'm asking because I'm interested in reproducing historical food and beverages and the source I'm working from (齊民要術, 6th century CE from NE China) just uses words like "glutinous rice (糯米)" without specifying whether the grains should be polished. If polishing wasn't an option at the time, or would have been specifically mentioned, then it's straightforward to interpret the recipes.
Jia's recipes are likely referring to white rice. In the book you're using, Jia Sixie's Qimin Yao Shu (齊民要術), Jia recommends husking and polishing rice. Because the oil in the rice bran quickly spoils, rice had to be polished after husking. In Africa and some parts of Asia, rice is typically parboiled beforehand, but it produces a taste that the Chinese considered undesirable. Instead, rice was polished well enough so that parboiling was not required in the process.
For further reading, see:
Bray, Francesca. Science and Civilisation in China Volume 6, Part 2: Agriculture. Cambridge: Cambridge University Press, 1984. 381-86.
Shi, Sheng-han. A Preliminary Survey of the Book Ch’i Min Yao Shu: An Agricultural Encyclopedia of the 6th Century. Peking: Science, 1974. 53-54 (an annotated English-language translation of Qimin Yao Shu).
Tangentially related to your question, it is also worth noting that not everyone in China eats a rice-based diet. The Science Magazine article referenced below makes clear that Chinese people in northern China are wheat growers and eat a wheat-based diet (noodles) rather than predominantly rice. Of course they also probably eat some rice (we don't grow rice in Virginia, but our family eats quite a lot of rice).
Science 9 May 2014:, Vol. 344 no. 6184 pp. 603-608, Large-Scale Psychological Differences Within China Explained by Rice Versus Wheat Agriculture by T. Talhelm et al.