The year is 1056, and two Buddhist kings reign over kingdoms in the Bay of Bengal region: Anawrahta, ruler of the Pagan Empire, and Vigrahapala III, the king of the Pala. A Mon Monk named Shin Arahan travels from his homeland, hoping to create a truer Theravada state than what he deems the Thaton Empire to have become. He plans to travel to Pagan, to take advantage of Anawrahta's dissatisfaction with the Buddhist clergy in hopes that the Burmese king will switch schools and create his perfect Buddhist state. The POD is a very simple one: as Arahan travels north, he trips, falls, and breaks his leg. He is forced to recover at a Buddhist monastery along his journey, and rest there for many months. He makes a full recovery, but by the time he reaches Pagan, it is 1057. King Anawrahta is at war with Thaton, and does not wish to speak to a monk from his nation's enemy.
Thus, Arahan travels west, to the empire of Pala, to the court of Vigrahapala III. Arahan, a skilled missionary who could have converted the Pagan king but a year before, manages to convince Vigrahapala III to leave Mahayana and become Theravada. Thus, when Sri Lanka's king Vijayabahu calls for aid from his fellow Theravada monarch to help him against the Hindu Cholas, it is Vigrahapala III who responds, sending aid from the north to help his fellow Buddhist. A couple years later, when Vijayabahu asks for Buddhist scriptures to help restore Buddhism in Sri Lanka, it is Vigrahapala III who sends them. And a few decades after that, when the Theravada orders of Sri Lanka have beyond recovered, and now seek to send missionaries, to spread their religion, they look not in the direction of Pagan, towards south-east Asia, but towards Pala, towards Buddhism's birthplace: India.