This monograph develops a new theoretical framework for interpreting Iranian civilizational history: the Continuity–Resonance Model (CRM). Contrary to linear historiographical approaches or rupture-based modernization theories, CRM conceptualizes Iranian civilization as a multi-layer semiotic-memory system in which structural patterns persist, reconfigure, and reemerge across long historical durations. The model identifies three core analytical dimensions: (1) Civilizational Memory Layers (CML), (2) Institutional Codification Layers (ICL), and (3) Resonance Activation Layers (RAL). Through these, the study reinterprets major historical transitions—including the Achaemenid administrative system, Sasanian codification, the Islamic boundary event, the emergence of the Persianate world, and modern Iranian state formation—as phases of systemic reorganization rather than civilizational rupture. By integrating insights from systems theory, semiotics (Lotman), longue durée historiography (Braudel), and Islamic-Iranian historiography, CRM proposes a unified explanatory model of civilizational persistence and transformation. The Iranian case is presented as an archetype of a long-memory civilization in which cultural, administrative, and symbolic structures exhibit structural recurrence across radically different political and ideological regimes. KEYWORDS Iranian civilization; civilizational theory; continuity and change; Persianate world; Sasanian Empire; Achaemenid Empire; Islamic Iran; systems theory; semiotics; longue durée; cultural memory; state formation; resonance theory