The Hakka (literally 'guest families') are not a separate ethnicity from the Han Chinese majority but rather the descendants of successive southward migrations across more than a thousand years. The category itself is created by movement: those who moved south during the Han collapse, the Tang–Song transition, the Mongol invasions, the Ming–Qing transition, and finally the 19th-century Taiping aftermath, settled as outsiders to the local populations they joined and developed institutions accordingly.
The most visible such institution is the tulou, the round and rectangular fortified earthen communal house of Fujian and Guangdong — entire patrilineal clans housed in a single defensive structure with shared courtyards, granaries, and worship halls. Lineage genealogies (zupu) tracked descent over many generations and allowed clan-level coordination for marriages, charity, and conflict resolution.
Education was treated as a path of escape from outsider status. Hakka over-representation in modern Chinese revolutionary leadership — Hong Xiuquan, Sun Yat-sen, Deng Xiaoping all had Hakka roots — and in overseas Chinese commerce, particularly in Southeast Asia, is best read as a function of these institutional patterns: tightly knit local communities, strong kin networks, schooling treated as obligation, and a self-image already organized around the experience of being elsewhere.