Njalahun, which has its center in Segbwema, and important town on the road to Kailahun from Kenema, traces its origin to a warrior and proficient trap setter named Nepoh who migrated from Bandajuma Kovay Gbuami across the Moa river. He came to present day Segbwema in search of plants from which he could produce rope to make his traps to catch animals. He found a large quantity of the plants on a hill called Dambeyema, and established himself there, eventually developing a prosperous farm. He married, and his wife became pregnant. She gave birth at the peak of the hungry season to a hideously ugly child, who she named Sei. Nepoh was lucky, however, as his crop that year had produced a tremendous yield much earlier than the other farmers. he told the people of the village that they could take his rice, but in exchange they must dance to entertain his ugly child, who could never hope to marry because of his ugly face. The people of the chiefdom obliged. The name Segbwema means “I came from seeing Sei”, referring to this first trip of the villagers to dance for the child. The name Njalahun, which refers to the whole chiefdom means “surrounded by water”, as the chiefdom is bordered by rivers. Though other families are recognized in the chiefdom, the chiefdom has been led by descendants of Nepoh since the 19th century.
Njajua - This house follows the lineage of Nepoh. Nepoh had two sons after Sei, who died early. This house follows the lineage of one of Sei’s younger brothers, Kangoi Jimmi Njajua, who became prominent and ruled the chiefdom after Nepoh’s death.
Gbawoh - This house follows the lineage of Nepoh’s third son Nepoh Farma Gbawoh. Farma Gbawoh had a son of the same name who was the first chief to be given the staff of the chieftaincy by the British.
Gbetuwa - This house follows the lineage of a sub-chief of Nepoh from Kambama village. Due to his diligence as a sub-chief Nepoh awarded him the right to stand for chief.
Samwova - This house follows the lineage of a warrior named Samwova who helped Nepoh defend the area.
Gbongboto - This ruling house was given the right to rule when Jan chiefdom was split and annexed to Njalahun in the 20th century. Two section, Fallay and Jongoh, joined Njalahun. The family though has never been able to win an election.