Indian (CBSE) based schools

So I learned that CBSE based schools in Nepal require students to learn Hindi as a subject. Not just that, school ma india ko national anthem samet gauuna parcha rey. Wtff?? A kid of a relative of mine studies there and they were like,” babu uncle haru lai india ko national anthem gaayera sunaiideu ta.”

Why teach Hindi and Indian anthem in Nepal to Nepalese students??