The social hierarchy in premodern Korea evolved over more than 2,000 years, from ancient times to the late Joseon period in the late 19th century when it gradually began to be abolished. The system of social stratification included the institution of nobi, which is subject to debate among scholars regarding whether it constituted slavery, serfdom, or both.

During the Joseon dynasty, which ruled Korea for over five centuries, society was largely stratified, with the yangban class at the top, followed by the common people, and then the nobi. The yangban class, composed of aristocratic scholars, held considerable power and wealth, often measured by their ownership of land and nobi.

The nobi, or slaves, were a distinct class with limited legal rights compared to freemen but possessed certain rights such as private property, subsistence wages, and contractual obligations through debt. However, the distinction between nobi and freemen blurred in some cases, particularly among the “non-resident” nobi who owned land and even nobi contracts, complicating the definition of slavery.

The prevalence of slavery varied over different periods in Korean history. Slavery was not widespread during the Three Kingdoms and Unified Silla periods, with slaves comprising no more than 10% of the population before the Joseon period. However, during the Joseon period, the nobi system became a major institution and an integral part of the economy, peaking between the 15th and 17th centuries before gradually declining in the 18th and 19th centuries.

At its peak, the nobi population comprised at least 30% of the total population, with significant variations between regions. The capital, Seoul, had a substantial nobi population, with a majority of households owning nobi. Despite efforts by the Joseon dynasty to undermine the nobi system through various reforms, including official abolitions in the 18th and 19th centuries, remnants of the system persisted until the late 19th and even mid-20th century.

In modern South Korea, slavery, or human trafficking, is illegal, although estimates suggest the existence of approximately 99,000 slaves as of 2018. In contrast, North Korea continues to practice slavery under the regime, with an estimated 10.4% of the population effectively enslaved as of 2018.

The terminology used to describe the nobi system, including terms such as “slave,” “serf,” or “servant,” remains a subject of debate among scholars due to its complex nature and historical context. While some argue for the use of specific terms, others prefer to use the Korean term “nobi” without translation to avoid Western connotations and implications.