These are Bu Quan coins cast and circulated by the Northern Zhou, with a value equivalent to five Wu Zhu coins. Subsequently, ten Bu Quan coins were rated as equivalent to one Wu Xing Da Bu, and a further conversion fixed ten Wu Xing Da Bu as equivalent to one Yong Tong Wan Guo.

The coins conform to the traditional Han cultural sphere format of a round coin with a square central perforation, with complete outer rims and inner borders on both obverse and reverse. The obverse inscription, “Bu Quan,” are engraved in yu zhu seal script and read from right to left. In the character quan (泉), the central vertical stroke is unbroken. Yu zhu seal script derives from Qin seal script and is so named for its rounded strokes and even thickness, typically written in a rectangular proportion. The reverse are plain and uninscribed.

In A3770 The inner border is exceptionally thick, a feature extremely rare among coinage of a comparable period, and it may represent a later imitation or re-engraving.

In the late Northern Wei period, repeated external threats and uprisings in the frontier garrisons facilitated the rise of Erzhu Rong, who suppressed rebellions on multiple occasions and came to dominate the court, arbitrarily deposing and installing emperors. After Erzhu Rong was lured into an ambush and killed by the Wei emperor, a power struggle ensued between Gao Huan, one of Erzhu Rong’s subordinates, and Erzhu Zhao, Erzhu Rong’s son. Gao Huan ultimately prevailed and installed Emperor Xiaowu. Dissatisfied with Gao Huan’s domination, Emperor Xiaowu relocated westward to Chang’an and sought the support of Yuwen Tai, who was based in the Guanzhong region and gradually emerged as the leader of an anti–Gao Huan power bloc. Gao Huan responded by installing another emperor in the east, resulting in the formal division between Eastern and Western Wei in AD 535. Following the split, Yuwen Tai progressively consolidated military and political authority: on the one hand, he relied on veterans from Wuchuan and Xianbei military traditions to establish the fubing militia system; on the other, he promoted institutional Sinicisation, rebuilding the bureaucratic apparatus and ritual order. Although Western Wei nominally continued to recognise emperors of the Yuan clan, real power was concentrated in the Yuwen family group. In the third year of Emperor Gong of Western Wei (AD 557), Yuwen Tai’s son Yuwen Jue received the abdication and proclaimed himself emperor, founding the Zhou dynasty, known to history as the Northern Zhou.

To sustain the combat effectiveness of the fubing system in its confrontation with Northern Qi, the Northern Zhou incurred substantial military expenditure. Emperor Wu of Northern Zhou, Yuwen Yong, first cast the Bu Quan, valued at five Western Wei Wu Zhu coins. In AD 574, the Wu Xing Da Bu was issued, rated at ten Bu Quan. After the accession of Emperor Jing, the Yong Tong Wan Guo coin was cast and circulated in the first year of the Daxiang reign (AD 579), valued at ten Wu Xing Da Bu. After several rounds of inflation, although these measures “greatly extracted profits from merchants,” the ratio of weight to nominal value meant that the Yong Tong Wan Guo had effectively been reduced to one one-hundred-and-sixty-sixth of the original Wu Zhu coin. This both stimulated widespread private and illicit minting and led to its rejection by the market. In the Hexi commanderies, gold and silver coins from the Western Regions were used for trade, while elsewhere older coins may have circulated concurrently, or silk textiles were adopted as an alternative medium of exchange.

Emperor Wu of Northern Zhou, originally named Yuwen Yong (AD 543–578), reigned from AD 560 to 578 and was the second emperor of the Northern Zhou. During his reign, he sought to weaken the power of the Guanzhong aristocracy, imperial in-laws, and dominant ministers, to strengthen imperial authority, and to implement a series of institutional reforms and military–administrative measures that rapidly enhanced the state’s strength. Yuwen Yong is particularly renowned for issuing edicts in the third and fourth years of the Jiande reign (AD 574–575) abolishing Buddhism and Daoism. Together with the anti-Buddhist policies of Emperor Taiwu of Northern Wei, Emperor Wu of Northern Zhou, Emperor Wuzong of Tang, and Emperor Shizong of Later Zhou, these measures are collectively known as the “Three Wu and One Zong suppression of Buddhism.” Beyond the aim of religious unification, the policy also sought to reclaim monastic land, population, and financial resources for military and state use. In foreign affairs, he successfully destroyed Northern Qi, bringing an end to the prolonged stalemate in northern China. Although diligent and frugal, Yuwen Yong died young, and many of his reforms and military initiatives were left unconsolidated. In the third year of the Daxiang reign (AD 581), Yuwen Yong’s grandson, Emperor Jing of Northern Zhou, abdicated the throne in favour of the imperial in-law and general Yang Jian. With this, the Northern Zhou came to an end, and the Sui dynasty was established.

這是一些北周所鑄行之「布泉」。一枚「布泉」當「五銖」五枚。後「布泉」十枚當「五行大布」一枚。又有「永通萬國」當「五行大布」十枚。

錢幣形制為漢文化圈傳統的方孔圓錢，面背外輪及內廓俱全。正面錢文為以玉箸篆鐫銘的「布泉」，自右而左順讀。「泉」字中央豎劃無斷筆。玉箸篆源於秦篆，因筆劃圓潤、肥瘦均勻而得名，多寫為長方形。錢幕光素無文。

A3770 之錢幕內廓極粗，於相近時代的貨幣形制中十分罕見，或為後世仿鑄或改刻。

北魏末年，外患與邊鎮變亂頻仍，使多次平亂的爾朱榮崛起，至擅行廢立。爾朱榮遭魏帝誘殺後，爾朱榮旗下高歡與爾朱榮之子爾朱兆相互爭權。高歡勝出後，立孝武帝。孝武帝因不滿高歡擅權，西遷長安，投靠以關中為中心，逐漸形成反高歡勢力的宇文泰。高歡因此另立東帝，東西魏於此分裂(公元535年)。宇文泰在東西魏分裂後逐步完成對軍政權力的整合，一方面倚重武川舊部與鮮卑軍事傳統，建立府兵制，另一方面推動制度漢化，重建官僚體系與禮制秩序。西魏名義上仍奉元氏皇帝，但實權已集中於宇文氏集團。至西魏恭帝三年(公元557年)，宇文泰之子宇文覺受禪稱帝，國號周，史稱北周。

為了府兵制戰力不墮，以與北齊對抗，北周軍事所費不貲。武帝宇文邕首鑄「布泉」，當西魏五銖五枚。公元574年又鑄「五行大布」，當「布泉」十枚。靜帝即位後，於大象元年(公元579年)鑄行「永通萬國」錢， 當「五行大布」十枚。經數次通貨膨脹後，雖「大收商賈之利」，但以重量和幣值的比例來看，「永通萬國」已減為原五銖錢的一百六十六分之一。一方面激起私鑄、盜鑄無數，一方面被市場棄用。河西各郡用西域金銀幣以作貿易，其他地方則可能雜用古錢，或改用絹帛。

北周武帝，原名宇文邕(公元543-578年)，公元560至578年在位，為北周第二位皇帝。其在位期間致力於削弱關隴貴族與外戚、權臣勢力，強化皇權，並推動一系列制度整頓與軍政改革，使北周國力迅速提升。宇文邕尤以建德三年、四年(公元574-575年)先後下詔廢除佛教與道教最為著名，與北魏太武帝、北周武帝、唐武宗、後周世宗的打壓佛教政策合稱「三武一宗滅佛」，其政策動機除宗教思想的統一外，也有收回寺院土地、人口與財力，以酬軍國之用的意圖。在對外方面，他成功攻滅北齊，結束北方長期對峙局面。宇文邕勤政節儉，然而英年早逝，其改革與軍事行動多未及鞏固即告中斷。大象三年(公元581年)，宇文邕孫，北周靜帝禪讓帝位於外戚將領楊堅。至此北周滅亡，隋朝建立。