The Bukar/Sadong populate the Serian area, mainly by Batang Kiri/Sg. Kedup, Tembawang Bukar and the Batang Kayan. They migrated about 600 years ago from Bugau (some say Sungkung), Kalimantan Barat to Tembawang Tampun, considered the origin point for most of the Bidayuh in Sarawak. Tembawang Tampun isn’t far from Mujat and Mongkos, which is now abandoned.
The Bisadong are divided into 15 subgroups who inhabit Serian.
Administratively, at the district level there is a Bidayuh Temenggong. Beneath him is the Pemanca. In Serian, there are 6 Penghulu who administrate 6 areas: Bukar (25 villages), Amo (13 villages), Tebedu (20 villages), Kedup (35 villages), Tebakang (21 villages) and Sadong (18 villages).
Most Bidayuhs are Christians, with very few pagans. In Serian there are 3 Bidayuh Muslim villages, Kpg. Buluh Bedup, Kpg. Darul Iman and Kpg. Darul Falah.
From Tembawang Tampun, they migrated towards what they called Tembawang Rutoi (Sinangkan Guyan) in 1370, which is near Kpg. Kujang Mawang. Now abandoned as the last settlers have moved to Kpg. Temong Mawang in 1750. It is believed that Tembawang Rutoi is the entry and transit point for most of the Bidayuh who came down from Tembawang Tampun into what is now Sarawak.
Today Serian is more accessible with the Pan-Borneo Highway. Yet there are still some areas which are inaccessible, needing river transport. Basic infrastructure is mostly in place, although the electricity and water supply can sometimes be erratic. Phone signals are mostly present in Serian town and in certain higher places within the hinterlands.