For example,
Nautiyals of Nauti village,
Semwals of Sem,
Bahugunas of Bughani,
Maithanis of Maithana,
Semaltis of Semalta,
Gairolas of Gairoli,
Chamolis of Chamoli,
Thapliyal of Thapli, etc......
It was usually the village inhabited the first that gave the nomenclature!