Mieszko was born in year 0922 in Poznan, Poland.1 Mieszko's father was Duke Ziemomysl of Poland and his mother was Gorka of Poland. His paternal grandparents were Leszek of Poland and <Unknown>; his. He was an only child. He died, at the age of 70 years, on May 25th, 0992.1
It is not clear from sources which wife sired which child, hence the multiplicity of Unknown spouses.
Mieszko I (c. 935-May 25 992), son of the semi-legendary Siemomysl, was the first (historically known) Piast duke of the Polans, which gave that name to a country later called Poland.
Mieszko was not his actual name, but given at a later time.
In either 964 or 965 (more probably) he married Dubrawka (or Dobrava), a daughter of Boleslaus I, duke of Bohemia. In 978 he married Oda von Haldensleben, daughter of Dietrich (Theoderic) of Haldensleben, count of the North March (965-985), after abducting her from the monastery of Kalbe.
The early career of Mieszko was dominated by fighting with the tribes of Wieletes and Volinians south of the Baltic Sea, and their ally, the Saxon count Wichman. Mieszko was baptised in 966 (probably under the influence of his Christian first wife or maybe in order to avoid confrontation with the Holy Roman Empire to the west) he built a church dedicated to Saint George at Gniezno.
At the time of the reign of Mieszko there was no single place serving as the capital instead he built serveral castles around his country. One the most important was Ostrow Lednicki (what is supported by the recent archeological findings). It was a ring-fort some 460 feet in diameter. Inside his residence, a fine stone palace, the country's first monumental architecture.
He had probably one sister of unknown name, and two brothers: one of them, name unknown, was killed in battle around 964; and the second, named Czcibor, died in the Battle of Cedynia in 972.
Mieszko I had pledged allegiance to emperor Otto I the Great, to emperor Otto II and again to emperor Otto III, however there is much dispute from the Polish side over this fact - mainly whether he was vassal from whole Poland, or from part Poland (the disputed fragment is "usque Varta fluvium"). One medieval chronicle also mentions that Mieszko pledged allegiance to margrave Gero, but since the chronicle itself is believed to be abstract of another which does not mention that fact, this is generally accepted nowaday as myth.
His reign began around 962 in Greater Poland (Wielkopolska), Cujavia, Masovia and possibly in eastern Pomerania. In the 960s he probably at least partially conquered western Pomerania, and in the 990's he conquered Silesia and Little Poland (Malopolska).
Much of his military activity was along the Baltic coast, in territory later called Pomerania. He defeated Count Dietrich of the Northern March at Cedynia in 972, and reached the mouth of the Oder/Odra river in 976. The decisive battle, fought in 979, ensured Mieszko's position as ruler of the area. The following year he celebrated his temporary conquest by dedicating a fortress at Gdansk. Settlements there have existed for millenniums and Pomeranian and Prussian territories overlap at the mouth of the Vistula River.
In 981 Mieszko I lost the land known only as Grody Czerwienskie to Vladimir I, prince of Kiev. In 986 he pledged allegiance to the Emperor Otto III, and helped him with wars with the Polabians. Shortly before his death he placed his state under the suzerainty of the Pope in a document usually called the Dagome Iudex.This Dagome Iudex indexes the lands of the Mieszko, referred as "Dagome" in document, and his wife, former nun Oda and her sons by him.
From his first marriage he had a son, his successor Boleslaus, and a daughter(s): the wife (as queen Sigrid the Haughty) of Eric the Victorious, king of Sweden and then (as queen Gunhilda) of king Sweyn Forkbeard of Denmark, and mother of king Canute of Denmark and England. Gunhilda and Sigrida may or may not be the same person, since most of sources is generally contradicting themselves on the issues regarding their history. The name for such daughter, "Swiatoslawa", is generally accepted amongst historians as best approximation on her Slavic name.
From his second marriage he had three sons, Mieszko, Lambert, and Swiatopolk.
Sources:
1. Abbrev: Pullen010502.FTW Title: Pullen010502.FTW Note: Call number: Text: Date of Import: Jan 5, 2002 2. Abbrev: Aiken, Tom Title: Aiken, Tom Note: Call number:
Mieszko Piast of Poland 
