Abstract: During China's market transition,early grassroots entrepreneurs of peasant origin universally faced the dual constraints of deficient resource endowments and the absence of formal institutions.As a quintessential endogenous market,Yiwu,Zhejiang,has consistently served as an exemplary bottom-up paradigm of Chinese modernization.This study draws on oral histories from Yiwu merchants and local chronicles to examine how grassroots actors navigated China's reform-era transformation through informal solidarities (Baotuan,“抱团”),which took four main forms:bargaining-driven,profit-driven,defensive,and mutual-aid.Through the lens of relational work theory,we explore the relational ties,trust mechanisms,and network structures that sustained these practices.The study finds that Baotuan acts as an alternative informal institution spontaneously forged by Chinese merchants to navigate intertwined social and economic logics.This mechanism not only elucidates Yiwu peasants'transition from local peddlers “bartering chicken feathers for sugar”(Jimao Huantang,“鸡毛换糖”) to transnational merchants of the “World's Capital of Small Commodities”,but also embodies the grassroots resilience underlying China's economic miracle.