sentences:  Up to the Late Pliocene or Pleistocene (more than two million years ago), the Upper Zambezi river used to flow south through what is now the Makgadikgadi Pan to the Limpopo River.The change of the river course is the result of epeirogenic movements that uplifted the surface at the present-day water divide between both rivers.Meanwhile, east, a western tributary of the Shire River in the East African Rift's southern extension through Malawi eroded a deep valley on its western escarpment.