It comprises the area west and southwest of Peshawar between the Tochi River to the north and the Gomal river to the south , forming part of Pakistan 's Federally Administered Tribal Areas ( FATA ) . Waziristan comprises the area west and southwest of Peshawar between the Tochi River to the north and the Gomal River to the south , forming part of Pakistan 's Federally Administered Tribal Areas ( FATA ) .