Pressure-temperature (P-T) paths observed in pelitic schists on either side of the Main Mantle Thrust in northern Pakistan record the dynamics of the collision between the Kohistan Island-Arc and Indian plate. Geothermometry studies, mineral reaction textures, and thermodynamic modeling of zoned garnets suggest that the rocks in the Kohistan Arc and the Nanga Parbat–Haramosh Massif experienced different pressure-temperature histories as a result of imbrication of these two terranes during thrusting. Rocks in the Kohistan Arc followed decreasing pressure-temperature paths, with early garnet growth occurring at high pressures (9.5 kbar) and later garnet growth at lower pressures (8.5 kbar). Conversely, rocks in the Nanga Parbat–Haramosh Massif record an increasing P-T path history. The early P-T history within the massif was at low pressures (4.0 kbar) and low temperatures (450°C). Later, both pressure and temperature increased to a maximum of 7.5 kbar and 580°C. The contrasting P-T paths observed within these two terranes provide evidence for overthrusting of the Kohistan Arc over the Nanga Parbat–Haramosh Massif along the Main Mantle Thrust.