Yiqu (simplified Chinese: 义渠; traditional Chinese: 義渠; pinyin: Yìqú; Wade–Giles: I-ch'ü; Old Chinese (444 BCE): *ŋaih-ga > Eastern Han Chinese: *ŋɨɑiᴴ-gɨɑ,^[1] or simplified Chinese: 仪渠; traditional Chinese: 儀渠; pinyin: Yíqú), was an ancient Chinese state which existed in the Hetao region and what is now Ningxia, eastern Gansu and northern Shaanxi during the Zhou dynasty, and was a centuries-long western rival of the state of Qin. It was inhabited by a semi-sinicized people called the Rong of Yiqu (Chinese: 義渠之戎), who were regarded as a branch of western Rong people by contemporary writers, whom modern scholars have attempted to identify as one of the ancestors of the minority people in Northwest China.^[2]

Contemporary textual evidence for the Yiqu is sparse, beginning only with the foundation of the state of Yiqu in the late eighth century BCE. It lasted approximately four-and-a-half centuries, until its end in the early third century. However, the origins of the Yiqu people as descendants of other "non-Huaxia" Chinese peoples have been traced back to the time of the Shang dynasty on the basis of textual scholarship and archaeological evidence, although this remains controversial (see "Ethnic identity of the Yiqu").^[3][4]

The capital of Yiqu has been identified as lying in Miaojuping (Chinese: 庙咀坪; pinyin: miáo jǔ píng) in Ning County, Qingyang, Gansu, on the confluence of four rivers. Archaeologists have discovered the remains of city walls and artefacts dating from the Zhou to Han dynasties. Textual evidence suggests it was abandoned before the Northern Wei period, when it was destroyed.^[14]

It is not known exactly how many cities the Yiqu built in their lands; from the number of cities cited which were taken by Qin according to historical texts, they may have numbered over twenty.^[14]

Not much is known about the culture of the Yiqu, other than they practised levirate marriages (including stepmothers) and cremated their deceased. The fact that the Yiqu leader is called "king" (Chinese: 王; pinyin: wáng) suggests a degree of political sophistication above a tribal chief.^[15] What is more likely is that they were an agricultural people, or at least had a mixed agricultural/pastoral economy. The fact that they were settled in established city-states indicates that they must have had significant agriculture to support themselves. This sets the Yiqu apart from the nomadic "non-Huaxia" peoples of East Asia such as the Xiongnu, who were either truly nomadic herders or migrated around in a transhumance fashion. Moreover, the fact that pottery objects and bricks (possibly used to build a palace) were discovered at the remains of the Yiqu capital further suggests a developed urban culture. The similarities of the type of bricks here and those excavated from remains of cities in other states of Zhou (such as Wei, Qi and Chu) may suggest a degree of trade between Yiqu and its neighbours.^[16]

In the pre-Han era, nomadic agriculturalists and pastoralists were considered alien peoples, whose history can be only tentatively traced through written sources and archaeological finds.^[17] Written sources identify the Yiqu a part of the Rong as the "Yiqu Rong" (Chinese: 義渠之戎; pinyin: yìqú zhī róng).^{[nb 7]} However, it cannot be said for certain that the Yiqu were a "Rong" people, or that there was a common "Rong" identity. Scholarly consensus has it that "Rong" was used ambiguously in Chinese sources as a blanket term for the various alien peoples around the Zhou territories, with no particular ethnic connotation.^[8]

If the Yiqu Rong are to be tentatively identified with any other "Rong" people, it would be the "Quan Rong" (also named "Xunyu" or "Xianyun"). This people attacked Zhou during the reign of Gugong Danfu (mid 12th century BCE), forcing the Zhou out of the city-state of Bin in the Jing River basin, which is where Yiqu established a state in the late eighth century.^[18] In addition, at the end of Western Zhou (781 BC–771 BC) the Quan Rong launched a series of attacks and invaded the Zhou capital, which weakened royal power and contributed to the moving of the Zhou capital to the east.^[19] As mentioned above, the Yiqu first appear as one of the many "Rong" which moved into the Central Plain around 720, settling in territory nominally controlled by the Zhou king. After this development, references to Xianyun, Xunyu, and Qian Rong in the Jing River basin are supplanted by "Yiqu" or "Yiqu Rong".^[7]

Furthermore, the Xianyun may be linked to the Siwa culture in the Tao River basin in what is now eastern Gansu, which dates to approximately the 14th century BCE, which some scholars believe is the remains of a Di branch of the Qiang. Indeed, the word "Yiqu" borrowed into ancient Chinese with the characters "義渠" (Old Chinese (444 BCE): */ŋaih-ga/) may be an Old Qiang toponym meaning "Four Waters", which corresponds to the four rivers which meet at the old Yiqu capital at present-day Miaojuping.^[18] However, evidence for this is based on alleged correspondence between the unattested Old Qiang language and Amdo Tibetan,^{[nb 8]} which is spoken in southern Gansu, and the assumption of a close relationship between these Tibetan speakers and the ancient Qiang and Rong, which cannot be firmly verified.^[17]

Sinologist Edwin Pulleyblank argued that the Xiongnu who later established the first nomadic empire on the Eurasian steppe were part of the Yiqu people, before the Qin general Meng Tian drove them north out of the Ordos region in 215 BC.^[20]