The Mizrahi Hebrew language or Oriental hebrew language refers to any one of the dialects of Biblical Hebrew used liturgical by Mizrahi Jews, that is, Jews living in Arab countries or further east, and typically speaking Arabic, Persian, Hindi, Chinese, or other languages of the Middle East and Asia. As such, Mizrahi Hebrew is actually a blanket term for many dialects.
Sephardi Hebrew is not considered one of these, although it has been spoken in the Middle East and North Africa. The Sephardim were expellees from Spain, and settled among the Mizrahim.
Hebrew was revitalized during the late 19th and early 20th century as the spoken language of Israel, called New Hebrew and also called Israeli Hebrew or Modern Hebrew.
The Soviet authorities considered Hebrew a "reactionary language" since it was associated with both Judaism and Zionism, and it was officially banned by the Narkompros (Commissariat of Education) as early as 1919.
Mizrahi (Oriental) Hebrew is actually a collection of dialects (including Yemenite or Temanit) spoken liturgically by Jews in various parts of the Arab and Islamic world.