How did the Burmese use the Irrawaddy River as they spread into central Myanmar?

As the ancestors of the Burmese arrived from the China-Tibet border area beginning in the 6th century, they utilized the Irrawaddy River primarily as a vital means of transport.1

By navigating the river, they were able to spread into the Kyaukse plain, where they established themselves as a major power in the region's rice-growing north. This expansion allowed them to consolidate control over the Irrawaddy and Sittang river valleys, as well as the essential trade routes connecting India and China. The river served as the principal axis for the development of the kingdom of Pagan, which flourished through the integration of rice cultivation and sophisticated irrigation networks supported by the river's resources.1