Sarlahi is one of the seventy-seven districts of Nepal. Being one of eight districts of Madhesh Province, it is an Outer Terai district, which borders Rautahat district to the west, Mahottari district

The Tharu or Tharuhat languages are any of the Indo-Aryan languages spoken by the Tharu people of the Terai region in Nepal, and neighboring regions of Uttarakhand, Uttar Pradesh and Bihar in India.