The term "First Reich" generally refers to the medieval era Holy Roman Empire, which existed from 962 to 1806. However, there are a few other terms that can be used as synonyms for this period in history. One common term is "Imperial Germany," which refers specifically to the period from the unification of Germany in 1871 to the end of World War I in 1918. Another term is simply "the Holy Roman Empire," which emphasizes the entity's religious roots and its connections to Christian Europe. The term "Germanic Empire" may also be used in some contexts, as, unlike the later "Second Reich," the Holy Roman Empire was not strictly a German state and included many other ethnic and linguistic groups.