Block from U+1A20 to U+1AAF. This block was introduced in Unicode version 5.2 (2009). It contains 127 codepoints.
The Wikipedia provides the following information on block Tai Tham:
Tai Tham is a Unicode block containing characters of the Lanna script used for writing the Northern Thai (Kam Mu'ang), Tai Lü, and Khün languages.