In reply to Martin Hore:
It's a confusingly all-encompassing term, it seems:
http://www.icimod.org/?q=1137
'[HKH region and adjacent mountain areas include: Afghanistan – all provinces except Kandahar, Helmand, Nimroz, Farah, and Herat; Bangladesh – Chittagong Hill Tracts; Bhutan – whole country; China – parts of Yunnan (Diqing, Nujiang, Dali prefectures), Sichuan (Ganzi, Aba, Liangshan prefectures), Gansu (Gannan, Wuwei, Zhangye prefectures), Xinjiang (Kashigar, Kezilesu, Hetian, Altai prefectures), whole of Tibet Autonomous Region and Qinghai; India – the 11 mountain states (Arunachal Pradesh, Himachal Pradesh, Jammu and Kashmir, Uttarakhand; Assam, Manipur, Meghalaya, Mizoram, Nagaland, Sikkim, and Tripura) and Darjeeling district of West Bengal; Myanmar – the states of Kachin, Chin, Shan and Rakkhain; Nepal – whole country; Pakistan – North Western Frontier Province (NWFP), Federally Administered Tribal Areas (FATA), Northern Areas, Ajad Jammu and Kashmir (AJK), and 12 districts of Baluchistan]'