Answer:
Nepal is a diverse country. The topography of Nepal is quite diverse. We have Himalayas, hills, and terai. Ethnically as well as culturally we have diversity. We have Sherpas, Thakalis, Bhotes e.t.c in the mountain region and Tamangs, Magars, Kirats, Brahmins, Chhetris e.t.c. in the hilly region, and similarly Yadavs, Tharus, and various other ethnic groups in the plains. We also have linguistic diversity as all the people in the Terai do not speak the same language, it is the same for the hills and mountains. And Natural resources are also randomly distributed.
So topography, ethnicity, resources, and language had been the bases of the division of the federal structure in Nepal.
The bases of the division of the federal structure in Nepal are ;
1.Historicity
2. Population
3. Regional base
4. Ethnicity and language
5. Geography