Usually short for 甘孜藏族自治州 (Ganzi Tibetan Autonomous Prefecture), one of two Tibetan prefectures in Sichuan. Ethnically Khampa Tibetan; covers the eastern Tibetan Plateau with peaks like Minya Konka (贡嘎山) and scenic areas Daocheng Yading (稻城亚丁) and Tagong (塔公). Name is a transliteration of Tibetan "dkar mdzes" (beautiful and pure).
mistakes
The standard reading is Gānzī, not Gānzǐ - even though 孜 in other contexts (孜然 "cumin") uses zī in first tone. Here both syllables are first tone.