The transition from the late 4th millennium BCE to the Bronze and Iron Ages along the northern and southern slopes of the Alborz Mountains is a major topic in archaeology, closely linked to the emergence of urbanism. Archaeological research indicates that with the end of Sialk III, many settlements, including those on the Qazvin Plain, collapsed. Similar processes occurred during the early 3rd millennium BCE in regions such as Kashan and Tehran. Although new settlements appeared in the Qazvin Plain during the later 3rd millennium BCE, the areas of Tehran, Qomrud, and Kashan were reoccupied only after a significant gap. In contrast, the northern flank of the Alborz displays a settlement history distinct from that of the southern side. While evidence for the influence of Sialk III in the north is limited, substantial occupation during the 3rd millennium BCE suggests divergent cultural developments on the two sides of the Alborz. This study draws on archaeological data from excavations and surveys in the northern and southern Alborz Mountains to examine Bronze Age (3rd millennium BCE) cultural developments. It highlights interaction networks linking the Gorgan Plain, southern Turkmenistan, Mazandaran, northeastern Iran, and the Central Plateau through exchanges of raw materials, technologies, and pottery traditions. Evidence from sites such as Tepe Hissar, Tureng Tepe, Ghal e-Ben, Ghal e-Kash, Tepe Kalar, and Qoli Darvish demonstrates cultural diversity, overlapping ceramic traditions, and continuous or discontinuous occupational sequences. The article emphasizes a contrast between the cultural hiatus of the Iranian Central Plateau and the flourishing development of the northern Alborz, particularly eastern Mazandaran and the Gorgan Plain, where regional interaction networks expanded. By contrast, the southern Alborz reflects migration, settlement disintegration, and environmental adaptation. Overall, the study identifies the Central Alborz as a key corridor for cultural interaction and interregional networks during the Bronze Age.