There are three main subdivisions within the Tibetic languages spoken within China (there are two others, which are however not spoken in China): Ü-Tsang, spoken only in Tibet itself and the basis of Standard Tibetan; Amdo, spoken in most of the Qinghai province; and Kham, spoken in eastern Tibet and the westernmost parts of the Sichuan province.
So Qinghai and the westernmost parts of Sichuan would be your best bets. Be warned, however, that the various subdivisions are mutually unintelligible.
Standard Tibetan (an Ü-Tsang language) is semi-tonal (one high and one low tone), whereas Amdo is non-tonal and Kham is “fully” tonal
Credit:stackoverflow.com‘