The collision between the Arabian and Eurasian plates is one of the key processes for understanding the evolution of the central segment of the Alpine–Himalayan belt. The development of the tectono-sedimentary systems of Zagros, Alborz, Talesh, and the Greater and Lesser Caucasus belts, as well as the depositional basins of the South Caspian, Moghan-Kura, and Central Iran, is fundamentally linked to this event. In addition to producing significant structural and tectonic changes at the regional scale, this collision led to major transformations in depositional patterns and in the evolution of back-arc and foreland basins. Among the most prominent indicators of this transition are the unconformities recorded in stratigraphic successions. These unconformities reflect processes such as pulsed uplift, abrupt changes in depositional regimes, variations in sedimentation rate, the influx of large volumes of clastic material, and short- to long-term interruptions in sedimentation. Numerous lines of evidence and previous investigations in the Zagros, Alborz, Talesh, and Caucasus belts show that the timing and characteristics of these unconformities are asynchronous and directly tied to the local dynamic of the orogenic belt. In the Moghan and South Caspian basins, the transition from deep-marine deposits to deltaic and continental units is accompanied by a marked increase in sedimentation rate, and the appearance of regional unconformities attests to the onset of the collisional phase and the associated mountain building. Correlation of unconformities across structural–sedimentary domains indicates that although the precise timing of events may differ slightly, a general pattern of progressively intensifying orogeny from the Eocene–Oligocene toward the Middle Miocene, and its culmination in the Pliocene–Quaternary, is evident throughout these mountain belts in association with the closure of the Neo-Tethys Ocean.