Tercia pars regni

The Duchy or Ducatus (Hungarian: dukátus or hercegség) is the denomination for territories occasionally governed separately by members (dukes) of the Árpád dynasty within the Kingdom of Hungary in the 11th-12th centuries. The symbol of the ducal power was a sword, while the royal power was represented by the crown.

Modern historians do not share a consensual view on the origins of the Duchy or territorial units administered by members of the royal family within the medieval Kingdom of Hungary.György Györffy writes that the Ducatus or "Duchy" developed from the command over the Kabars and other ethnic groups which joined the federation of the Hungarian tribes. According to his opinion, this command was initially, even before the Hungarian conquest of the Carpathian Basin around 895, bestowed upon the heir to the supreme head of the Hungarian tribal federation, in accordance with the customs of the Turkic peoples of the Eurasian steppes. Therefore, Györffy continues, the crown prince's command over these ethnic groups transformed, in the course of the 10th century, into his authority over the territories where they settled. Tringli says that it is possible that Koppány's domains in Transdanubia and Saint Emeric's territories (he bore the title of Duke of Russians) were duchies too in accordance with steppe tradition. On the other hand, Gyula Kristó, who rejected Györffy's theory, writes that the Duchy only came into being when King Andrew I of Hungary granted one third of his kingdom to his younger brother, Béla around 1048. He cites the Illuminated Chronicle which clearly states that this was the "first division of the kingdom".

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