Inner Sleeping Robe original: 裻 du; often refers to a garment with a prominent back seam or a specific type of inner robe used for sleeping

The Classic of Poetry original: Shijing (詩經); the oldest collection of Chinese poetry, dating from the 11th to 7th centuries BCE says, "Embracing the quilt and the inner robe."

The Analects original: Lunyu (論語); the foundational text of Confucianism states, "One must have a sleeping robe, the length of which is one and a half times the body's length." This pertains to the customs of the Shang and Zhou dynasties c. 1600–256 BCE.

The Miscellaneous Records of the Western Capital original: Xijing Zaji (西京雜記); a collection of historical anecdotes regarding the Han dynasty court at Chang'an says that when Zhao Feiyan the Empress of Emperor Cheng of Han, famous for her slender figure and dancing skill was elevated to Empress, her younger sister, the Lady of Bright Deportment original: Zhaoyi (昭儀); a title for a high-ranking palace consort, in this case referring to Zhao Hede, presented her with thirty-five inner robes, including the "Mandarin Duck Inner Robe." Thus, the specific name du began to be used during the Han dynasty 206 BCE – 220 CE.

Mattress original: 褥 ru

The Inner Biography of the Yellow Emperor original: Huangdi Neizhuan (黃帝內傳); a legendary account of the life and spiritual pursuits of the mythical Yellow Emperor states that the Queen Mother of the West original: Wangmu (王母); a major goddess in Chinese mythology associated with immortality set out for the Emperor a "Bed of Seven Treasures for Ascending to Truth," and spread upon it a "Mattress of Flowery Down and Rhinoceros Light" likely referring to a luxurious material with a shimmering or iridescent quality. It is suspected that these two items the bed and the mattress originated from this era.

When the Lady of Bright Deportment Zhao Hede presented gifts to the Empress, the thirty-five items also included a "Mandarin Duck Mattress."