South Asia has attracted global attention because it has experienced rapid GDP growth over the last two decades. What is not so well known is that South Asia is the least integrated region in the world. South Asia has opened its door to the rest of the world but it remains closed to its neighbors. Poor market integration, weak connectivity, and a history of friction and conflict have resulted in two South Asias. The first South Asia is dynamic, growing rapidly, highly urbanized, and is benefiting from global integration. The second South Asia is rural, land locked, full of poverty, and lagging. The divergence between the two South Asias is on the rise. Policy makers in South Asia have realized that countries and regions can not grow in isolation. The unique geography of South Asia-distance and density--has the potential to raise growth through increased flow of labor, capital, ideas, technology, goods and services within the region and with the rest of the world. Most lagging regions, in terms of both per capita income and poverty incidence, in South Asia are either land-locked or located in the border areas. Regional cooperation and market integration will unlock the development of these lagging regions in South Asia.