 Since then Limbuwan comprises all the area between Arun River and Koshi River in the west to Kunchenjunga Mountains and Mechi River in the east.In the beginning of the 15th century, the descendants of King Sirijonga became weak and Limbuwan again fell into chaos and anarchy.At the time Lowland Limbuwan Kingdom of Morang was ruled by King Sangla Ing.