Lääne-Viru County in the context of "Harjumaa"

Ida-Viru County (Estonian: Ida-Viru maakond or Ida-Virumaa; Russian: Ида-Вируский уезд, romanized: Ida-Viruskij uezd) is one of the 15 counties of Estonia. It is the most northeastern part of the country. The county contains large deposits of oil shale – the main mineral mined in Estonia. Oil shale is used in the production of shale oil and in thermal power plants. The capital of the county is the town of Jõhvi which is administratively united with the Jõhvi Parish; nevertheless, Narva is the largest town in the county in terms of population and at the same time the third-largest city in Estonia after Tallinn and Tartu.

In January 2019, Ida-Viru County had a population of 136,240 – constituting 10.3% of the total population in Estonia. It borders Lääne-Viru County in the west, Jõgeva County in the southwest and Russia (Leningrad Oblast) in the east. It is the only county in Estonia where Russians constitute the majority of population (73.1% in 2010), the second highest being Harju (28%).

Harju County (Estonian: Harju maakond or Harjumaa) is one of the fifteen counties of Estonia. It is located in northern Estonia, on the southern coast of the Gulf of Finland, and it borders Lääne-Viru County to the east, Järva County to the southeast, Rapla County to the south, and Lääne County to the southwest. The capital and largest city of Estonia, Tallinn, is located in Harju County. Harju is the largest county in Estonia in terms of population, as almost half (45%) of Estonia's population lives in Harju County.

Virumaa or Viru (Latin: Vironia; Low German: Wierland; Old Norse: Virland) is an historical region in northeastern Estonia and a medieval independent Estonian county (maakond). In most part, the historical Virumaa region overlaps with modern Lääne-Viru ("West Viru") and Ida-Viru ("East Viru") counties.

Medieval people of Virumaa, the Vironians, built many strongholds, like Tarwanpe (modern Rakvere) and Agelinde (now Punamägi Hill in Äntu village). Vironians were divided into five clans (kilikunda), Maum (in Estonian "Mahu"), Laemund (Lemmu) also known as Pudiviru, Askele, Revele (Rebala), Alentagh (Alutaguse). Like other Estonian tribes, Vironians remained predominantly pagan before Northern Crusades in the 13th century.

Järva County (Estonian: Järva maakond or Järvamaa; German: Jerwen; Latin: Jervia) is one of 15 counties of Estonia. It is located in the central part of the country, and it borders Lääne-Viru County to the east, Jõgeva County to the southeast, Viljandi County to the south, Pärnu County to the southwest, Rapla County to the west, and Harju County to the north. In 2022, Järva County had a population of 29,693, constituting 2.7% of the total population in Estonia.

The Duchy of Estonia (Swedish: Hertigdömet Estland; Estonian: Eestimaa hertsogkond; German: Herzogtum Estland), also known as Swedish Estonia (Swedish: Svenska Estland), was a dominion of the Swedish Empire from 1561 until 1721 during the time that most or all of Estonia was under Swedish rule. The territory was eventually ceded to Russia in the Treaty of Nystad, following its capitulation during a plague outbreak in the Great Northern War.

The dominion arose during the Livonian War, when the northern parts of present-day Estonia — Reval (Tallinn) and the counties of Harjumaa, Western Virumaa, Raplamaa and Järvamaa — submitted to the Swedish king in 1561, and Läänemaa in 1581. It is also colloquially known as the "good old Swedish times" (Estonian: vana hea Rootsi aeg) by Estonians, but this expression was not used before the following Russian rule, in the beginning of which the situation of Estonian peasantry declined rapidly; to gain the support of the German Baltic nobility, Russia gave them more power over the peasantry.