Yaroslav the Wise in the context of "Principality of Halych"

Kievan Rus', also known as Kyivan Rus', was the first East Slavic state and later an amalgam of principalities in Eastern Europe from the late 9th to the mid-13th century. Encompassing a variety of polities and peoples, including East Slavic, Norse, and Finnic, it was ruled by the Rurik dynasty, founded by the Varangian prince Rurik. The name was coined by Russian historians in the 19th century to describe the period when Kiev was preeminent. At its greatest extent in the mid-11th century, Kievan Rus' stretched from the White Sea in the north to the Black Sea in the south and from the headwaters of the Vistula in the west to the Taman Peninsula in the east, uniting the East Slavic tribes.

According to the Primary Chronicle, the first ruler to unite East Slavic lands into what would become Kievan Rus' was Varangian prince Oleg the Wise (r. 879–912). He extended his control from Novgorod south along the Dnieper river valley to protect trade from Khazar incursions from the east, and took control of the city of Kiev, laying the foundation of the state and becoming prince of Kiev. Sviatoslav I (r. 943–972) achieved the first major territorial expansion of the state, fighting a war of conquest against the Khazars. Vladimir the Great (r. 980–1015) spread Christianity with his own baptism and, by decree, extended it to all inhabitants of Kiev and beyond. Kievan Rus' reached its greatest extent under Yaroslav the Wise (r. 1019–1054); his sons assembled and issued its first written legal code, the Russkaya Pravda, shortly after his death.

Harald Sigurdsson (Old Norse: Haraldr Sigurðarson; c. 1015 – 25 September 1066), also known as Harald III of Norway and given the epithet Hardrada in the sagas, was King of Norway from 1046 to 1066. He unsuccessfully claimed the Danish throne until 1064 and the English throne in 1066. Before becoming king, Harald spent 15 years in exile as a mercenary and military commander in Kievan Rus' and chief of the Varangian Guard in the Byzantine Empire. In his chronicle, Adam of Bremen called him the "Thunderbolt of the North".

In 1030, the fifteen-year-old Harald fought in the Battle of Stiklestad alongside his half-brother Olaf Haraldsson. Olaf sought to reclaim the Norwegian throne, which he had lost to Danish king Cnut two years previously. Olaf and Harald were defeated by forces loyal to Cnut, and Harald was forced into exile to Kievan Rus'. Thereafter, he was in the army of Grand Prince Yaroslav the Wise, becoming captain, until he moved on to Constantinople with his companions around 1034. In Constantinople, he rose quickly to become the commander of the Byzantine Varangian Guard, seeing action on the Mediterranean Sea, in Asia Minor, Sicily, possibly in the Holy Land, Bulgaria and in Constantinople itself, where he became involved in the imperial dynastic disputes. Harald amassed wealth whilst in the Byzantine Empire, which he shipped to Yaroslav in Kievan Rus' for safekeeping. In 1042, he left the Byzantine Empire, returning to Kievan Rus' to prepare to reclaim the Norwegian throne. In his absence the Norwegian throne had been restored from the Danes to Olaf's illegitimate son Magnus the Good.

Rus' Khaganate or Kaganate of Rus is a name applied by some modern historians to a hypothetical polity suggested to have existed during a poorly documented period in the history of Eastern Europe between c. 830 and the 890s.

The fact that a few sparse contemporaneous sources appear to refer to the leader or leaders of Rus' people at this time with the word chacanus, which might be derived from the title of khagan as used by groupings of Asian nomads, has led some scholars to suggest that his political organisation can be called a "k(h)aganate". Other scholars have disputed this, as it would have been unlikely for an organisation of Germanic immigrants from the north to adopt such a foreign title. Some historians have criticised the concept of a Rus' Khaganate, calling it a "historiographical phantom", and said that the society of 9th-century Rusʹ cannot be characterised as a state. Still other scholars identify these early mentions of a Rus' political entity headed by a chacanus with the Kievan Rus' state commonly attested in later sources, whose princes such as Vladimir the Great (r. 980–1015), Yaroslav the Wise (r. 1019–1054), and perhaps Sviatoslav II of Kiev (r. 1073–1076) and Oleg I of Chernigov (r. 1097–1115) were occasionally identified as kagans in Old East Slavic literature until the late 12th century.

The Russkaya Pravda (sometimes translated as Rus' Justice, Rus' Truth, or Russian Justice) was the legal code of Kievan Rus' and its principalities during the period of feudal fragmentation. It was written at the beginning of the 12th century and remade during many centuries. The basis of the Russkaya Pravda, the Pravda of Yaroslav, was written at the beginning of the 11th century. The Russkaya Pravda was a main source of the law of Kievan Rus'.

In spite of great influence of Byzantine legislation on the contemporary world, and in spite of great cultural and commercial ties between Byzantium and Kievan Rus', the Russkaya Pravda bore no similarity whatsoever to the law of the Byzantine Empire. The absence of capital and corporal punishment rather reflects Norse jurisprudence.

The history of Ukraine spans thousands of years, tracing its roots to the Pontic steppe—one of the key centers of the Chalcolithic and Bronze Ages, Indo-European migrations, and early horse domestication. In antiquity, the region was home to the Scythians, followed by the gradual expansion of Slavic tribes. The northern Black Sea coast saw the influence of Greek and Roman colonies, leaving a lasting cultural legacy. Over time, these diverse influences contributed to the development of early political and cultural structures.

Ukraine enters into written history with the establishment of the medieval state of Kievan Rus'. In Dnieper Ukraine, the tribe of Polans played a key role in the formation of the state, adopting the name Rus' by the 9th century. The term is believed to have connections to the Varangians, who contributed to the state's early political and military structure. By the 10th–11th centuries, Kievan Rus' had grown into one of the most powerful and culturally advanced states in Europe, reaching its golden age under Vladimir the Great and Yaroslav the Wise, who introduced Christianity and strengthened political institutions. However, internal conflicts among Kyivan rulers, along with increasing pressure from Turkic nomads in Southern Ukraine, gradually weakened the state.

Estrid Svendsdatter of Denmark (also known as Estrith or Astrith; sometimes called Margaret; fl. 1017–1032; c. 990s – after 1057 and before 1073) was a prominent Danish princess and titular queen of the Jelling dynasty, half-sister of Cnut the Great and wife of the magnate Ulf Jarl. She was the mother of Sweyn II Estridsen, during whose reign she was commonly styled dronning (“queen”) in Denmark, though she was never queen regnant nor a king's consort. Through Estrid, Sweyn traced his claim to the Danish throne and founded the matronymic House of Estridsen, which ruled from 1047 to 1412.

Medieval sources diverge on several points of her life. She was a daughter of Sweyn Forkbeard, but her mother is variously identified in sources as Sigrid the Haughty or, in earlier scholarship, as the Slavic princess sometimes called Gunhild of Wenden, a view now generally rejected. After Sweyn's death in 1014, Estrid came under Cnut's guardianship. He married her to a son of Grand Prince Vladimir the Great or Yaroslav the Wise, but the prince died shortly afterwards. Several western chroniclers, including Rodulfus Glaber and Adam of Bremen, record a proposed or short-lived marriage with the duke of Normandy (probably Robert I, Duke of Normandy), though the precise details remain uncertain. By the early 1020s, she was married to the English magnate Ulf Thorgilsson, who later served as regent in Denmark. By marriage she was thus, successively, a Russian princess, duchess of Normandy and a Danish noblewoman.