The city was first mentioned in historical chronicles in 1019 as Bierascie when Kievan duke Yaraslau The Wise fought with another duke, the leader of the slavonic tribe of Dreulane Svyatopolk. Svyatopolk was defeated and escaped to Bierascie which at that time was part of the Duchy of Turau. In 11th century Bierascie was an old Rusian trade center and a fortress on the border with Polish and Lithuanian territories. Located on the islands at the confluence of the rivers Mukhavets and Boog, Bierascie was at the intersection of two trade ways leading through Slavonic lands to Poland, Baltics and Western Europe. One of the ways was going along the Western Boog river from Galich and Valyn (nowadays it is Western Ukraine). The second way along Mukhavec, Pina, Prypiac, Dniepr rivers connected Bierascie with Kiev, the Black Sea and the Middle East.

Because  of its border location Brest often was in the center of military actions, and it changed hands many times. In 11-12 centuries the city belonged to Turau and the Galich-Valyn Duchies. In 1020 Bierascie was occupied by the Polish Duke Balyaslau The Courageous. The Kievan Duke Yaraslau The Wise undertook three attempts to return the city into the Old Russian State (in 1022, 1031 and 1044), and  in 1044 Bierascie finally was returned to the Kievan Duchy, the Old Russian State. In 1117 Bierascie was subdued by the great Kievan Duke Vladimir Monomakh. Since 1142 the Dukes of the Galich and Valyn headed the city. In the second part of the 12th century Bierascie became the center of the small feudal duchy called Land of Bierascie which was part of Galich-Valyn Duchy. In 1164 the Lithuanian Duke Skirmunt took Bierascie but did not own it for a long time. Unsuccessful were the attempts of the Polish king Kazimierz the Second in 1179 and 1182 to join Bierascie to Poland. In 1213 the Polish King Leszko occupied Bierascie but in 1222 Valyn duke Vasil'ka returned the city to the bosom of the Land of Bierascie. In the beginning of the 13th century the troops of the Polish king Konrad Mazovetski occupied the city but the population of Bierascie resisted and the king had to return the city to the Galich-Valyn' Duchy. In the middle of the 13th century the Bierascie Land was invaded by Mongols. There is no historical evidence about the depredation of Bierascie by them. Mongols were weakened by fights with Slavonic Duchies and could not move further to Western Europe. Many times Bierascie was besieged by enemies, sometimes it was burnt down and ruined, but every time it was reconstructed.

The View of Ancient Bierascie
To defend their territories from invaders the Slavonic dukes built fortifications - castles and towers. In the 12th century a castle and a fortification to harbor the trade caravans were built in the city. Bierascie served as a customs where the merchants paid their taxes for carrying goods. In 1276 Valyn duke Vladimir Vasil'kovich erected high stone tower in the city. Also he ordered to build up another tower on the Lyasnaya river in Belavezhskaya Puscha to defend the northern territories of his duchy. The city of Kamyanec soon appeared near the second tower in the primeval forest. The tower in Kamyanec is still standing as a witness of those events. The forest moved for 15-20 kilometers from the tower and only from the top one can see the BelavezhskayaPuscha stretching for dozens of miles.

Scene of the ancient Bierascie
To the North of Bierasce, an old Lithuanian-Belarusian state, the Great Duchy of Lithuania, was emerging. The state appeared on the territories of baltic tribes half-assimilated by Slavs. The dukes of Lithuania managed to escape the subjugation to Rusian Dukes and the state was growing and getting stronger. Since the end of the 12th century the Lithuanian territories were attacked by crusaders who wanted to subdue the Baltic and the Rusian territories. To resist the crusaders' threat, the peace treaty between Rusian and Lithuanian dukes was signed in 1219.