The Cyrillic Extended-B block spans U+A640–U+A69F, 96 codepoints in Plane 0 (Basic Multilingual Plane). Every one of them is assigned in Unicode 16.0.
All of its characters belong to the Cyrillic script.
By general category: 37 uppercase letters (Lu), 37 lowercase letters (Ll), 13 non-spacing marks (Mn), 3 enclosing marks (Me), 3 modifier letters (Lm), plus smaller groups.
The first 78 arrived in Unicode 5.1 (2008); later additions came in 6.0 (2), 6.1 (9), 7.0 (6), 8.0 (1).