Book of the Later Han in the context of "Wakoku"

The Book of Han (Chinese: 漢書), finished in 111 CE, is one of the Twenty-Four Histories and covers the Western, or Former Han dynasty from the first emperor in 206 BCE to the fall of Wang Mang in 23 CE. The work was composed by Ban Gu (32–92 CE), an Eastern Han court official, with the help of his sister Ban Zhao, continuing the work of their father, Ban Biao. They modelled their work on the Records of the Grand Historian (c. 91 BCE), a cross-dynastic general history, but theirs was the first in this annals-biography form to cover a single dynasty. It is the best source, sometimes the only one, for many topics such as literature in this period. The Book of Han is also called the Book of the Former Han (前漢書; Qián Hàn shū) to distinguish it from the Book of the Later Han (後漢書; Hòu Hàn shū) which covers the Eastern Han period (25–220 CE), and was composed in the fifth century by Fan Ye (398–445 CE).

Buyeo (Korean: 부여; Korean pronunciation: [pu.jʌ]; Chinese: 夫餘/扶餘; pinyin: Fūyú/Fúyú), also rendered as Puyŏ or Fuyu, was an ancient kingdom that was centered in northern Manchuria in modern-day northeast China. It had ties to the Yemaek people, who are considered to be the ancestors of modern Koreans. Buyeo is considered a major predecessor of the Korean kingdoms of Goguryeo and Baekje.

According to the Book of the Later Han, Buyeo was initially placed under the jurisdiction of the Xuantu Commandery, one of Four Commanderies of Han in the later Western Han. Buyeo entered into formal diplomatic relations with the Eastern Han dynasty by the mid-1st century AD as an important ally of that empire to check the Xianbei and Goguryeo threats. Jurisdiction of Buyeo was then placed under the Liaodong Commandery of the Eastern Han. After an incapacitating Xianbei invasion in 285, Buyeo was restored with help from the Jin dynasty. This, however, marked the beginning of a period of decline. A second Xianbei invasion in 346 finally destroyed the state excepting remnants in its core region; these survived as vassals of Goguryeo until their final annexation in 494.

Fan Ye (398 – 23 January 446), courtesy name Weizong (蔚宗), was a Chinese historian, philosopher, and politician of the Liu Song dynasty during the Southern and Northern dynasties period. He was the compiler of the historical text Book of the Later Han. The fourth son of Fan Tai (范泰), Fan Ye was born in present-day Shaoxing, Zhejiang, but his ancestral home was in Nanyang, Henan. After his birth, he was made heir of another male relative Fan Hongzhi (范弘之).

He was a noted atheist who heavily criticised Buddhism, Yin and Yang, and the concept of the Mandate of Heaven. To this end, he cited Zhang Heng's scientific studies as evidence.

Hua Tuo (c. 140–208), courtesy name Yuanhua, was a Chinese physician who lived during the late Eastern Han dynasty. Historical texts, such as Records of the Three Kingdoms and Book of the Later Han record Hua Tuo as having been the first person in China to use anaesthesia during surgery. He used a general anaesthetic combining wine with a herbal concoction called mafeisan (麻沸散; literally "cannabis boil powder"). Besides being respected for his expertise in surgery and anaesthesia, Hua Tuo was famous for his abilities in acupuncture, moxibustion, herbal medicine and medical daoyin exercises. He developed the Wuqinxi (五禽戲; literally "Exercise of the Five Animals") from studying the movements of the tiger, deer, bear, ape and crane.

The Xubu (Chinese: 須卜; pinyin: Xūbǔ; Wade–Giles: Hsü-pu; LHC: *sio-pok) was a tribe of the Xiongnu that flourished between 3rd century BCE and the 4th century CE. Chinese annals noted that the Xubu tribe replaced the Huyan tribe, which was an earlier maternal dynastic tribe of the dynastic union with the paternal dynastic tribe Luandi. The traditional system of conjugal unions is a form of the nomadic exogamic society. The male members of the maternal dynastic line were not eligible to be chanyu, only the male members of the Luandi line, whose father was a Luanti Chanyu, and mother was a Xubu Khatun (Queen) were eligible to be chanyu. A Xubu could only become a chanyu after a palace coup.

The Huyan tribe moved from the Right (Western) Wing, where the maternal dynastic tribe is traditionally assigned, to the Left (Eastern) Wing. The Book of the Later Han (chapter 89, l. 7b) stated that of the noble tribes other than Luanti, Huyan, Xubu, Qiulin and Lan, Huyan already belonged to the dominating Left Wing, and Lan and Xubu belonged to the Right Wing. The Book of the Later Han also names the dynastic Luandi tribe with a composite name Xulianti, implying a merger of the two dynastic lines.