Early this month I had the privilege of trekking through the western foothills of Gauri Shankar from Barhabise to Dolakha-so close to Kathmandu and yet devoid of crowds of trekkers. We climbed high above the Sun Kosi into remote mountain pastures, basked in rhododendron groves, goggled at langur monkeys, and were warmly welcomed by the nuns of the Bigu gomba, some of whom had rolled up their sleeves to help build a new block there. We marvelled at neat terraces of barley and wheat, swam in chilly rivers, and watched the lightning.

Aside from all those wonders, we were struck by the constant atmosphere of warm camaraderie and the diversity of the 11 staff on our camping trek. The sirdar was a Sherpa and his deputy a Rai. The marvellous cook a Bahun, his assistants a Sherpa and a Rai. Our porters were two Chhetris, two Tamangs, and two Newars.

And these people had not been gathered from all over Nepal. The porters were from a single village above Barhabise, and for six days we walked through a patchwork land, passing settlements of Gurungs, Tamangs, Sherpas, Chhetris, Thangmis, and more.

Look at the ethnic conflict prevalent in much of the world, and you realise that this diversity is one of Nepal's greatest assets. Of course the country is wracked by hierarchy and discrimination, but society here still has a tolerant and open dimension that outsiders should envy. In the past, politics hasn't taken on the ethnic, caste, or sectarian dimensions seen, for example, in India.

Yet some now want an ethnic carve-up of Nepal. In front of me is the Maoists' map of the country. My trekking route is in "Tamang-saling", the Kathmandu Valley in "Newa", Everest in "Kirant", the eastern tarai in "Madhesh", the western tarai in "Tharuwan". The Federation of Indigenous Nationalities and other ethnic organisations are now demanding similar ethnically-based structures for the country. And given the tarai tensions, we now officially have federalism, though we don't know what kind.

Federalism, of course, can be highly successful, especially in large countries where decentralisation makes sense. Germany, the US, and Canada are successfully federal but not, largely, on an ethnic basis. But history suggests that ethnically-based federalism is a dubious idea. The former Yugoslavia was an ethnic federation and it collapsed. Apartheid South Africa drew up internal ethnic borders to keep the black population divided; with democracy, it redrew those borders on a non-ethnic basis. Belgium is federally divided between French-speakers and Dutch-speakers and barely functions as a single country (intriguingly, its monarchy is the one unifying factor).

Closer to home, the LTTE's attempt to carve-up Sri Lanka along ethnic lines has brought 24 years of war. India's federation is mainly on linguistic lines and is reasonably successful, but it has brought some problems: violence in the north-east, and sectarian politics, for instance, in Mumbai, where the extremist Shiv Sena wants Marathi supremacy in the state.

In any case, Nepal differs from all of these in that its ethnic and caste groups are so much more mixed up. Think of the patchworks of villages around the country; or the diversity within villages and towns.

Nepal's status quo is not, of course, fine. The Bahun-Chhetri domination of state affairs has alienated most Nepalis. The exclusion of dalits, janajatis and madhesis-and, of course, women-is shameful and has been to the extreme detriment of the country. Nepal must wage a social revolution to counteract that history: maybe measures like quotas are needed, maybe non-ethnic federalism will help. But playing with ethnicity is dangerous and can turn neighbour against neighbour.