Böszörmény, also Izmaelita (Hysmaelita / Ishmaelites) or Szerecsen (Saracens), is a name for the Muslims who lived in the Kingdom of Hungary in the 10–13th centuries. Some of the Böszörmény probably joined the federation of the seven Magyar tribes during the 9th century, and later smaller groups of Muslims arrived in the Carpathian Basin. They were engaged in trading but some of them were employed as mercenaries by the kings of Hungary. Their rights were gradually restricted from the 11th century on, and they were coerced to accept baptism following the establishment of the Christian Kingdom of Hungary. They "disappeared" (probably became Christian) by the end of the 13th century.
Modern authors claim that several groups of Muslims migrated to the Carpathian Basin in the course of the 10th–12th centuries; therefore, the Muslims living in the Kingdom of Hungary were composed of various ethnic groups. Most of them must have arrived from Volga Bulgaria, but toponyms suggest that Muslim (káliz: khalyzians) people arrived also from Khwarezm; these latter (or part of them) may have formed one of the three tribes of the Kabars who joined the federation of the Magyar tribes in the 9th century.
The Arab historian and geographer, al-Mas'ūdī recorded in the 10th century that the heads of the tribal confederation had welcomed Muslim merchants and the merchants could even convert some of the Magyars into Islam.Al-Bakrī also mentioned that the Magyars ransomed the Muslims who had been captured in the neighboring countries. In the 10th century, Ibrahim ibn Yaqub described the Muslim merchants who arrived in Prague from the territories of the Magyars and traded with slaves and tin. The Gesta Hungarorum recorded that lots of Muslims arrived in the Carpathian Basin from Volga Bulgaria during the reign of Taksony, Grand Prince of the Magyars (c. 955 – before 972) and they settled down there. The work of the Muslim traveler, Abu Hamid al-Garnati, who spent three years in the kingdom (1150–1153), proves that the Muslims living in the Kingdom of Hungary were composed of two groups: the Khwarezmians and the Maghrebians (Böszörmény). He was entrusted by King Géza II of Hungary to recruit soldiers among the Maghrebians (Böszörmény) living east of the Carpathian Basin. The Byzantine historian John Kinnamos mentioned that káliz warriors were captured during the war between the kingdom and the Byzantine Empire in 1165 and the Emperor Manuel I Komnenos removed some of them to Byzantine territories.