you can find a book "modern nepal" by rishikesh shah in most univeristy and public libraries. There is a map of nepal before the treaty of sugauli. It extends from tista in the east and kangda in teh west, and upto gorakhpur in the south. the northern border stays at the himalayas. The Sugauli treaty lost nepal a chunk of land and the present nepal was formed except the 4 districts of mahakali zone, which was rewarded to nepal (actually jung bahadur rana) after the sepoy mutiny in india.