Block from U+0300 to U+036F. This block was introduced in Unicode version 1.1 (1993). It contains 112 codepoints.
The Wikipedia provides the following information on block Combining Diacritical Marks:
Combining Diacritical Marks is a Unicode block containing the most common combining characters. It also contains the Combining Grapheme Joiner, which prevents canonical reordering of combining characters, and despite the name, actually separates characters that would otherwise be considered a single grapheme in a given context.