Japanese conquest of Burma main attack westward from Rahaeng in Thailand across the Kawkareik Pass. The 16th Indian Infantry Brigade of the 17th Indian Division guarding this approach retreated hastily westward. The Japanese division advanced to Moulmein at the mouth of the Salween River which was garrisoned by the 2nd Burma Infantry Brigade. The position was almost impossible to defend, and had the River Salween, almost wide, behind it. The 2nd Burma Brigade was squeezed into a progressively tighter perimeter, and eventually retreated over the river by ferry on 31 January after abandoning a large amount of supplies and equipment. Part of the force
Burma Plate Ma) further faulting developed and the Burma and Sunda microplates began to "break off" from the larger Eurasian plate. After a further series of transform faulting, and the continuing subduction of the India Plate beneath the Burma plate, backarc spreading saw the formation of the marginal basin and seafloor spreading centre which would become the Andaman Sea, a process well-underway by the mid-Pliocene (3–4 Ma). On December 26, 2004, a large portion of the boundary between the Burma Plate and the Indian Plate slipped, causing the 2004 Indian Ocean earthquake and tsunami. This megathrust earthquake had an estimated moment magnitude