Poland's boundries in the time of Boleslaw the Bold (solid line) and Kazimierz the Great (dashed line)
The Origins of Poland
According to Polish myth, the Slavic nations trace their ancestry to three brothers who parted in the forests of Eastern Europe, each moving in a different direction to found a family of distinct but related peoples. Fanciful elements aside, this tale accurately describes the westward migration and gradual differentiation of the early West Slavic tribes following the collapse of the Roman Empire. About twenty such tribes formed small states between A.D. 800 and 960. One of these tribes, the Polanie or Poliane ("people of the plain"), settled in the flatlands that eventually formed the heart of Poland, lending their name to the country. Over time the modern Poles emerged as the largest of the West Slavic groupings, establishing themselves to the east of the Germanic regions of Europe with their ethnographic cousins, the Czechs and Slovaks, to the south.
In spite of convincing fragmentary evidence of prior political and social organization, national custom identifies the starting date of Polish history as 966, when Prince Mieszko (r. 963-92) accepted Christianity in the name of the people he ruled. In return, Poland received acknowledgment as a separate principality owing some degree of tribute to the German Empire (later officially known as the Holy Roman Empire--see Glossary). Under Otto I, the German Empire was an expansionist force to the West in the mid-tenth century. Mieszko accepted baptism directly from Rome in preference to conversion by the German church and subsequent annexation of Poland by the German Empire. This strategy inaugurated the intimate connection between the Polish national identity and Roman Catholicism that became a prominent theme in the history of the Poles.
Mieszko is considered the first ruler of the Piast Dynasty (named for the legendary peasant founder of the family), which endured for four centuries. Between 967 and 990, Mieszko conquered substantial territory along the Baltic Sea and in the region known as Little Poland to the south. By the time he officially submitted to the authority of the Holy See in Rome in 990, Mieszko had transformed his country into one of the strongest powers in Eastern Europe.
Mieszko's son and successor Boleslaw I (992-1025), known as the Brave, built on his father's achievements and became the most successful Polish monarch of the early medieval era. Boleslaw continued the policy of appeasing the Germans while taking advantage of their political situation to gain territory wherever possible. Frustrated in his efforts to form an equal partnership with the Holy Roman Empire, Boleslaw gained some non-Polish territory in a series of wars against his imperial overlord in 1003 and 1004. The Polish conqueror then turned eastward, extending the boundaries of his realm into present-day Ukraine. Shortly before his death in 1025, Boleslaw won international recognition as the first king of a fully sovereign Poland.