Block from U+A000 to U+A48F. This block was introduced in Unicode version 3.0 (1999). It contains 1165 codepoints.
The Wikipedia provides the following information on block Yi Syllables:
Yi Syllables is a Unicode block containing the characters of the Liangshan Standard Yi script for writing the Nuosu, or Yi, language.
Note that the name for U+A015 is a misnomer, as the character is actually a syllable iteration mark corresponding to "w" in Yi romanization.