Sei Bingai is a subdistrict of Langkat Regency. It borders Binjai to the north, Kuala and Salapian to the west, Deli Serdang Regency to the east, and Karo Regency to the south. Most people in Sei Bingai are Karo. A majority of people in Sei Bingai are Muslims, as the Karo are predominantly, but not entirely Christian in this area.