How do diffusion and contagion spread ethnic conflict to other countries?

In the context of political science, ethnic conflicts often transcend national borders through two primary mechanisms: diffusion and contagion.1

Diffusion occurs when an ethnic conflict in one state serves as a catalyst for similar unrest in another. This process is driven by shared economic or political conditions; when an ethnic movement achieves success, it provides moral incentives and imagery that motivate and mobilize groups in other countries facing comparable circumstances.1

Contagion (or escalation) refers to the direct spread of conflict across borders, typically occurring in neighboring countries where an ethnic minority has kinfolk. This dynamic often involves the movement of foreign fighters and the active participation of local elites who employ them.1

Beyond these mechanisms, the internationalization of such conflicts is frequently exacerbated by the involvement of external actors, including diasporas and foreign powers, who may provide financial, political, or military support to further their own agendas. While borders formally delineate state sovereignty, they are often porous, allowing for the cross-border flow of arms and combatants that fuels violent mobilization.12