Tongyangxi was a unique marriage practice in ancient China in which families adopted young girls as future daughters-in-law and raised them within their households. These girls were adopted during adolescence and raised alongside their betrotheds until the consummation of their marriage upon both reaching maturity. This practice was most prevalent among peasants in the countryside during a time known as the Old Society, a term for the period between the late Qing dynasty and the founding of the People’s Republic of China. This paper analyzes the cultural, economic, and political influences in the Old Society that shaped the unique nature of tongyangxi. It finds that the emphasis on patriarchy, family duty, and female obedience in Confucianism, a pillar of ancient Chinese philosophy, was crucial in prompting the adoption of daughters-in-law from a young age. Furthermore, economic instability in the Old Society’s largely agrarian and family-labor-focused economy caused families to seek tongyangxi to avoid the financial burdens of traditional marriage and secure labor. Finally, political tolerance in the Qing Dynasty and the persistence of social norms under the Nationalist Government allowed for the perpetuation of the practice. This paper contributes to scholarly discussions by analyzing the underpinnings of the Old Society that led to the prevalence of tongyangxi. Understanding tongyangxi within its historical context provides insight into how cultural, economic, and political factors influenced family structures and gender roles in traditional Chinese society.