The continents have drifted vast distances since the Quaternary. A massive rift of land which broke away from Africa along the East African Rift has moved across what was the Indian Ocean and collided with the southernmost corner of Southeast Asia. As the two landmasses came together, a vast inland sea was created between in the area that was once the Bay of Bengal. The massive forces created by the colliding tectonic plates buckled the landmass, giving rise to a volcanic mountain range along the line of fusion. Over time, the inland sea became almost entirely cut off from the oceans to the south.