sentences:  The plain also borders the Menoreh hills in the southwest and Prambanan Plain in the southeast.The Progo River runs through the center of this plain, from its source on the slope of Mount Sundoro to the southern coast of Java facing the Indian Ocean.It has been a significant location in Central Javanese history for over a millennium, as it contains traces of the Sailendra dynasty as well as Borobudur and associated locations.