Fig. 1: Proposed structures for the subducted lithosphere that was between India and Tibet in the early Eocene.

a The convergence history between India and Eurasia in different plate reconstructions^{11,12,13,14,15}. The thick brown line illustrates the average convergence rate of these different studies, and the thick blue line shows the corresponding total convergence. b Early Paleogene position of the Indian Subcontinent with different hypotheses (or model types) for the nature and structure of the ‘lost’ lithosphere between India and Tibet^{1,2,4,11,17,20,21,22}. Based on the numerical modeling in this study (also in Liu et al., 2021a⁴⁴), the external terrane was also part of the Indian Subcontinent (Type 6). We propose a wedge-shaped continental margin between the terrane and Indian Subcontinent, based on the recent recognition that the hard collision happened ~20 Myr earlier in regions towards the western Himalayan syntaxis than in eastern regions²². C. Margin- Continental Margin. Type 2, 3, and 4 models are inconsistent with the geological record but help to demonstrate the effects of various initial conditions on model evolution (more discussion in the main text).