Terms for subject Historical containing that of

English	Russian
a practice that has fallen out of favor	обычай, вышедший из употребления (Alex_Odeychuk)
member of a religious sect that practiced flagellation	хлыст
... of that time	... того времени (Alex_Odeychuk)
receive the name of "Kharkiv" as an honorific for its actions in the liberation of that city	получить название Харьковской за освобождение этого города (wikipedia.org Oleksandr Spirin)
the countries that were formerly part of the Soviet Union	страны, в прошлом входившие в состав Советского Союза