People of which among the following countries are also known as Magyars?

The Magyars (Hungarians) spread rather widely through the Holy Roman Empire, taking their Reformed faith with them.
Within the empire, they built up a large system of schools, elementary through university, and did much for Hungarian cultural life.
For many years after the Treaty of Versailles, the Magyar people, split between
Hungary, Romania had hoped that eventually they would be reunited
in one political unit and that their church would also be reunited.
Source: www.britannica.com