Looks like the problem is with the way the block was implemented (as site mods can verify on this page, which lists all blocked tags and other blocked input for the site).
The regex for this particular tag-blocking seems to specifically check for a tag name consisting solely of
history- followed by one or more "word characters" (i.e. alphanumeric characters or underscores).
So as written, something like
history-of matches the regex (meaning history-of can't be created as a tag). But just
history doesn't match the regex (since it doesn't have the hyphen or a word character after it), and neither does
history-of-science (since it has at least one non-word character: the hyphen) – meaning it doesn't stop history or history-of-science from being (re)created as tags.
The tag block has now been fixed. A dev has updated the regex for the blocklist to ensure that
history will be blocked (i.e. can no longer be created as a tag), as well as anything beginning with the word
history followed by any combination of dashes and alpha-numeric chars.
The tag still needs to be manually removed from the questions it's on (which I believe can be done by moderators or other users). Once this tag is "burninated", users should no longer be able to recreate it.