In the 9th century, East Francia, the First Bulgarian Empire and Great Moravia ruled the territory of the Carpathian Basin. The Magyars advancing through the Carpathian Basin encountered the Hungarian-speaking Székely people who inhabited the land at that time.
The Mongols returned to Hungary in 1285, but the newly built stone-castle systems and new tactics (using a higher proportion of heavily armed knights) stopped them.
The invading Mongol force was defeated The Kingdom of Hungary reached one of its greatest extents during the Árpádian kings, yet royal power was weakened at the end of their rule in 1301.
The country switched to using the Latin language, and until as late as 1844, Latin remained the official language of Hungary. The most powerful and wealthiest king of the Árpád dynasty was Béla III, who disposed of the equivalent of 23 tonnes of pure silver a year.
This exceeded the income of the French king (estimated at 17 tonnes) and was double the receipts of the English Crown.
The second element eri, 'man, men, lineage', survives in Hungarian férj 'husband', and is cognate with Mari erge 'son', Finnish archaic yrkä 'young man'.