Beidi or Northern Di (Chinese: 北狄; pinyin: Běidí; Wade–Giles: Pei-ti) were groups of people who lived to the north of what was then China during the Zhou Dynasty. By the end of the dynasty they were mostly conquered or absorbed by the Chinese.
The ancient Chinese classed their neighbors by compass direction, calling them the Northern Di, Southern Man, Eastern Yi and Western Rong. Bei Di may simply mean 'northern foreigners' or it may have been a definite people whose nature was explained by its location. We have too little information to assign them to any ethnic or linguistic group. The four names, or combinations of them like 'Yi-Di' are often used to mean barbarians.
The Di seem to have lived in a horizontal band from the upper Ordos Loop and across northern Shanxi to the state of Yan north of Beijing. This area was a transition zone between the emerging Chinese civilization and the steppe peoples to the north. They seem to have practiced a mixed pastoral, agricultural and hunting economy. Other groups of Di seem to have lived interspersed between the Chinese states. To their north was the emerging steppe society whom the Chinese later called Hu. To the southwest the Rong lived along the northwest frontier of China. The Di and Rong are often associated and both were considered more warlike and less civilized than the Yi and Man.
The Di had walled towns and fought on foot. They were often enemies and sometimes allies of the various Chinese states. We hear of trade, treaties, marriage alliances and Chinese politicians fleeing to exile among the Di.
The Bai (White) Di lived in the west and the more warlike Chi (Red) Di to the east. The state of Zhongshan near Beijing was founded by the Bai Di. It adopted Chinese material culture but was never considered properly Huaxia (Chinese). Other Di groups were the Chang Di and Xianyu. The state of Fei and the Xianyu were part of the White Di confederation.
The scattered references to the Di do not add up to a coherent history. According to legend the ancestors of Zhou dynasty lived among the Rong and Di until Gu Gong Danfu led then away to the mid-Wei River valley where they built their capital near Mount Qi (before 1107BC). In 676-651 Duke Xian of Jin conquered a number of Rong and Di groups. In 662 the Di drove the Rong out of Taiyuan. In 662-659 the state of Xing was nearly destroyed by the Chi Di until it was rescued by Qi. In 660BC the Chi Di took the capital of Wey and killed its king, but were driven out by Qi. From 660 to 507 Jin fought many wars with the Di, destroying Chi Di state of Lu in 594, 'subjugating' them in 541 and being severely defeated by the Xianyu Di in 507. In 640 the Di were allied with Qi and Xing against Wey and in 636 the Di helped the Zhou king against the state of Cheng. In 531 Jin attacked the Xianyu and Fei. By about 400bc most of the Di and Rong had been eliminated as independent polities. Zhongshan was conquered by Wei in 406, regained its independence in 377 and was conquered by Zhou in 295. Circa 283-265 Tian Dan fought some Di who seem to have lived within the area of the Chinese states.