4 Zhu Xiaojian, Southern dynasties, Song Dynasty, Plain reverse

The "Xiaojian" denomination takes its name from the Xiaojian reign period of Emperor Xiaowu of Liu Song, one of the four short-lived Southern Dynasties that controlled the Yangtze River basin while the north remained under non-Han rule. These coins were cast in such vast quantities — and with so little control over metal content — that they collapsed in purchasing power almost immediately, prompting successive imperial edicts attempting to regulate private casting that were largely ignored.

The plain reverse distinguishes this from contemporaneous issues that carried additional cast marks or secondary inscriptions added to combat forgery.