The Great Hungarian Plain (also known as Alföld or Great Alföld, Hungarian: Alföld [ˈɒlføld] or Nagy Alföld) is a plain occupying the majority of the modern territory of Hungary. It is the largest part of the wider Pannonian Plain. (However, the Great Hungarian plain was not part of the ancient Roman province Pannonia). Its territory significantly shrank due to its eastern and southern boundaries being rewritten by the new political borders created after World War I when the Treaty of Trianon was signed in 1920.