When the great kingdom of Pagan declined politically in the late thirteenth and early fourteenth centuries, its territory devolved into three centers of power and a period of transition occurred. Then two new kingdoms arose: the First Ava Dynasty in Upper Myanmar and the First Pegu Dynasty in Lower Myanmar. Both originated around the second half of the fourteenth century, reached their pinnacles in the fifteenth, and declined before the first half of the sixteenth century was over. Their story is the only missing piece in Myanmar’s mainstream historiography, a gap this book is designed to fill.