Fig. 3: Initial and boundary conditions for the numerical models.

a Type 1 models (Runs 1–4, Supplementary Figs. S5 and S6), where the incoming plate before the Indian Subcontinent indentation is purely continental. ICP-Incoming Continental Plate (i.e., Greater India). Strong Litho.- i.e., Asian interiors. Weak Litho.- i.e., Tibetan terranes. b Type 2 models (Runs 5–6, Supplementary Figs. S7 and S8), where the incoming plate north of the Indian Subcontinent is purely oceanic (i.e., Greater Indian Basin). The ocean has an assumed age of 40 Myr¹. Type 3 (Run 7–10, Supplementary Figs. S9 and S10) and Type 4 (Run 11–14, Supplementary Figs. S11 and S12) models share the same initial condition as Type 2, except that there is an additional 200 km or 900 km long ICP between the oceanic segment and Indian Subcontinent in Type 3 and type 4 models, respectively (Fig. 1b)^4,21. c Type 5 models (Runs 15–22, Supplementary Figs. S13–S16), where a preceding terrane separates with the Indian Subcontinent by an 80 Myr oceanic block. The terrane Lithosphere is 500 km long in Runs 15–18 and 600 km long in Runs 19–22 (Supplementary Table S2). The compositional density of the ocean lithospheric mantle is 3.39 g/cm³, and that of the terrane lithospheric mantle is 3.37 g/cm³. d Type 6 models (Runs 23–40, Fig. 5, Supplementary Figs. S17–S20) (Supplementary Table S2). These are similar to Type 5 but with a more buoyant lithosphere (compositional density anomaly of the lithospheric mantle −0.02 g/cm³ and the lithospheric thermal age −40 Myr) behind a more buoyant terrane (the compositional density anomaly of its lithospheric mantle is −0.03 g/cm³). This portion of the plate has a thin (~10 km) crust as required by the Himalayan crustal volume⁴⁴ and thus more resembles a thinned continental margin. The terrane length in the Type 6 models is ~600 km long⁴⁴. The enlarged views demonstrate the material distribution in each lithospheric ___domain.