Kingdom of the first Piasts (Regnum Poloniae) was the state formed by the Boleslaus I of Poland in 1025 during his coronation. However, the legal base for existence of this Christian kingdom was established in 1000 during the Meeting in Gniezno, when Poland was recognized as the state by Holy Roman Empire and the Pope.
The official language: Latin (written), Polish (spoken)
The first historic member, Duke Mieszko I (reigned 96292), began the unification of Poland and introduced Christianity.
With the death (1370) of his son, Casimir III, the Piast dynasty ended in Poland; it was finally succeeded by the Jagiello dynasty.
The Silesian Piasts, as vassals of Bohemia and mediate princes of the Holy Roman Empire, retained the ducal title and continued to hold the duchy of Oppeln until 1532 and the principalities of Brieg, Liegnitz, and Wohlau until their extinction in 1675.
Under Duke Mieszko I (reigned 96092) of the Piast dynasty began (966) the conversion of Poland to Christianity.
The Piasts expanded their domains in wars against the German emperors, Hungary, Bohemia, Pomerania, Denmark, and Kiev, and in 1025 Boleslaus I (reigned 9921025) took the title of king.
The main line of the Piast dynasty ended with the death (1370) of Casimir III, whose enlightened economic, administrative, and social policies included the protection of the Jews.