Great Hungarian Plain in the context of "Hortobágy National Park"

The Pannonian Basin, with the term Carpathian Basin being sometimes preferred in Hungarian literature, is a large, mainly lowland area in southeastern Central Europe, briefly described as a sedimentary basin. Under the geopolitically changed conditions created by World War I and the ensuing Treaty of Trianon, the geomorphological term Pannonian Plain was also used for roughly the same region, referring to the lowlands in the area occupied by the Pannonian Sea during the Pliocene. However, Hungarian geographers consider the term "Pannonian Plain" not only unhistorical but also topographically highly erroneous. Regarding the name as such, they are arguing in terms of ancient history, namely that the northern and eastern boundary line of the namesake Roman province of Pannonia was formed by the River Danube, thus the Great Hungarian Plain was not part of the original Pannonia province.

Budapest is the capital and most populous city of Hungary. It is Hungary's primate city with 1.7 million inhabitants and its greater metro area has a population of about 3.3 million, representing one-third of the country's population and producing above 40% of the country's economic output. Budapest is the political, economic, and cultural center of the country, among the ten largest cities in the European Union and the second largest urban area in Central and Eastern Europe. Budapest stands on the River Danube and is strategically located at the center of the Pannonian Basin, lying on ancient trade routes linking the hills of Transdanubia with the Great Plain.

Budapest is a global city, consistently ranked among the 50 most important cities in the world, belongs to the narrow group of cities with a GDP over US$100 billion, named a global cultural capital as having high-quality human capital, and is among the 35 most liveable cities in the world. The city is home to over 30 universities with more than 150,000 students, most of them attending large public research universities that are highly ranked worldwide in their fields, such as Eötvös Loránd University in natural sciences, Budapest University of Technology in engineering and technology, MATE in life sciences, and Semmelweis University in medicine. Budapest also hosts various international organizations, including several UN agencies, the WHO Budapest Centre, IOM regional centre, the EU headquarters of EIT and CEPOL, as well as the first foreign office of China Investment Agency. Budapest opened the first underground transit line on the European continent in 1896, which is still in use as M1 Millennium Underground, and today the fixed-track metro and tram network forms the backbone of Budapest's public transport system and transports 2.2 million people daily, making it a significant urban transit system.

Ottoman Hungary (Hungarian: Török hódoltság, lit. 'Turkish subjugation') encompassed the parts of the Kingdom of Hungary which were under the rule of the Ottoman Empire from the occupation of Buda in 1541 until the liberation of the region under Habsburg leadership during the Great Turkish War (1683–1699), until the Treaty of Karlowitz in 1699. The territory was incorporated into the empire, under the name Macaristan. For most of its duration, Ottoman Hungary covered Southern Transdanubia and almost the entire region of the Great Hungarian Plain.

Ottoman Hungary was divided for administrative purposes into Eyalets (provinces), which were further divided into Sanjaks. Ownership of much of the land was distributed to Ottoman soldiers and officials with the remaining territory being retained by the Ottoman state. As a border territory, much of Ottoman Hungary was heavily fortified with troop garrisons. Remaining economically under-developed, it became a drain on Ottoman resources. During the centuries long three-way Hungarian–Habsburg–Ottoman wars the Hungarian population was highly decimated.

An oppidum (pl.: oppida) is a large fortified Iron Age settlement or town. Oppida are primarily associated with the Celtic late La Tène culture, emerging during the 2nd and 1st centuries BC, spread across Europe, stretching from Britain and Iberia in the west to the edge of the Hungarian Plain in the east. These settlements continued to be used until the Romans conquered Southern and Western Europe. Many subsequently became Roman-era towns and cities, whilst others were abandoned. In regions north of the rivers Danube and Rhine, such as most of Germania, where the populations remained independent from Rome, oppida continued to be used into the 1st century AD.

The Hungarian conquest of the Carpathian Basin, also known as the Hungarian conquest or the Hungarian land-taking (Hungarian: honfoglalás, lit. 'taking/conquest of the homeland'), was a series of historical events ending with the settlement of the Hungarians in Central Europe in the late 9th and early 10th century. Before the arrival of the Hungarians, three early medieval powers, the First Bulgarian Empire, East Francia, and Moravia, had fought each other for control of the Carpathian Basin. They occasionally hired Hungarian horsemen as soldiers. Therefore, the Hungarians who dwelt on the Pontic-Caspian Steppe east of the Carpathian Mountains were familiar with what would become their homeland when their conquest started.

The Hungarian conquest started in the context of a "late or 'small' migration of peoples". The Hungarians took possession of the Carpathian Basin in a pre-planned manner, with a long move-in between 862–895. Other theories assert that the Hungarians crossed the Carpathian Mountains following a joint attack by the Pechenegs and Bulgarians in 894 or 895. They first took control over the lowlands east of the river Danube and attacked and occupied Pannonia (the region to the west of the river) in 900. They exploited internal conflicts in Moravia and annihilated that state sometime between 902 and 906.

Hungary in its modern (post-1946) borders roughly corresponds to the Great Hungarian Plain (the Carpathian Basin) in Central Europe.

During the Iron Age, it was located at the crossroads between the cultural spheres of Scythian tribes (such as Agathyrsi, Cimmerians), the Celtic tribes (such as the Scordisci, Boii and Veneti), Dalmatian tribes (such as the Dalmatae, Histri and Liburni) and the Germanic tribes (such as the Lugii, Marcomanni). In 44 BC, the Sarmatians, Iazyges moved into the Great Hungarian Plain. In 8 AD, the western part of the territory (the so-called Transdanubia) of modern Hungary formed part of Pannonia, a province of the Roman Empire. Roman control collapsed with the Hunnic invasions of 370–410, the Huns created a significant empire based in present-day Hungary. In 453 they reached the height of their expansion under Attila the Hun. After the death of Attila, the empire collapsed in 455, and Pannonia became part of the Ostrogothic Kingdom. The western part of the Carpathian Basin was occupied by the Longobards and the eastern part by the Gepids. In 567, the Avars occupied the territory ruled by the Gepids. In 568, the Longobards moved to Italy from Transdanubia, and the Avars also occupied that territory, Khagan Bayan I established the Avar Khaganate. The Avars were defeated by the Franks and Bulgars, and their steppe-empire ended around 822.