The Huadong Valley or Hualien-Taitung Valley (), also known as East Rift Valley or the Longitudinal Valley, is a long and narrow valley located between the Central Mountain Range and the Coastal Mountain Range. It is also recognized as a plain area which stretches for about 180 kilometers near the eastern coast of Taiwan, passes from Hualien City at the north to Taitung City at the south. It was called or simply Nakasendō during the era of Japanese rule.