The district has an area of 3,310 kmÂ ( 1,278 sq . miles ) ; the population according to the 1998 census was 448,310 . Lying between the Miranzai Valley and the Durand Line , the district has an area of 3,310 kmÂ ( 1,278 sq . miles ) . Its population was 448,310 , according to the 1998 census .