The actual boundaries of the Ruhr vary slightly depending on the source, but a good working definition is to define the Lippe and Ruhr as its northern and southern boundaries respectively, the Rhine as its western boundary, and the town of Hamm as the eastern limit.
In the Middle Ages, local power was vested primarily in the counts (Grafen) of Berg, Mark and Cleves. The left bank of the Rhine was held by the Archbishop of Cologne. The Hellweg was an important trade route crossing the region from Duisburg to Dortmund and beyond as far as the rivers Weser and Elbe. The most important towns of the region were concentrated along the Hellweg.
As a result of the Congress of Vienna, the entire area came under the control of Prussia (the state had already gained possessions there). This event was almost concomitant with developments which would eventually make the region one of the most important industrial areas in the world.
In 1946, the state of North Rhine-Westphalia came into being centred on the Ruhr. Nowadays, its hitherto important coal and steel industries have drastically declined and the region is in a state of re-adjustment.
Carboniferous period
During the Carboniferous Period, in the Paleozoic era, which began 360 million years ago and ended 300 million years ago, layers of slate, coal and sandstone were formed. 400 to 300 million years ago, new mountains were uplifted during the Variscan mountain-building period.
During the Silesian period, layers were deposited which became seams of coal over a period lasting millions of years. During this period there was a constant shifting between marshy conditions and overflowing seas such that the depositing of plant material and sediment from the sea resulted in the current situation of coal layers separated by stone layers.
The main representatives of flora in the coal marshes were of the genus Lepidodendron and genus Sigillaria, tree-like plants, which belong to the plant classification Lycopodiophyta. Members of both genus reached heights of up to 40 meters with a trunk diameter of over a meter.
Cretaceous Period
In the Cretaceous, 135 million to about 66 million years ago, the region was submerged under a tropical ocean. In its waters lived ammonites. On the floor of the sea, a thick layer of marl formed. The sediments covered the layers of carbon and contained also the shells of giant ammonites.
Quaternary The Ice Age brought changes between warm and cold weather. During the Drenthe Stadium of the Wolstonian Stage, an ice sheet over Northern Germany covered the Ruhr and reached as far as the northern hills of the Central Uplands. The shape of the middle and lower Ruhr valley is due to meltwaters and the powerful force of the ice. Meltwater from the glaciers flowed westwards through the Ruhr valley. Where Essen lies today, this flow was temporarily hindered by a barrier of ice and rocky debris, forming an enormous lake which filled the valley at Schwerte.
Pre-history 80,000 B.C. – The region of the present-day Ruhr was already settled during the Neanderthal period, around 80,000 years ago. During the building of the Rhine-Herne Canal in 1911, stone tools and traces of encampment with bones from woolly rhinoceros, bison and mammoth were found in Herne. Humanoids also settled elsewhere in the Emscher valley. Similar finds in the 1960s were made in Bottrop. 8700 BC. – In November 1978 stone-age flint instruments were found on the Kaiserberg in Duisburg which belong to the later phases of the last Ice Age and can be dated to about 9000 to 8000 BC. The oldest remains of modern humans in the area of the current Ruhr stem from the early Middle Stone Age. They were discovered in Spring 2004 in the Blätterhöhle in Hagen-Hohenlimburg. 6000–4500 BC – several settlements are known in the regions of Bochum, Hagen and Dortmund from the Linear Pottery culture and the Rössen culture. In Spring 2004, the skeletons of several humans from the Michelsberg culture were discovered in the Blätterhöhle in Hagen-Hohenlimburg. Among them was the skeleton of a 17–22-year woman. These finds are the single source of information for burials from this period in the current Rhine-Ruhr district.
Antiquity
100 BC – Threat to the Celtic inhabitants by the Germanic Sicambri 12 BC – Construction of the Roman camp Asciburgium on the present-day boundary between Moers and Duisburg, the Kastell Werthhausen in present-day Duisburg-Rheinhausen and the legionary camp Vetera at Birten left of the Rhine and therefore on the boundary of the district and the later province of Germania Inferior. 11 BC – In order to control the Sicambri settled on the right-bank of the Rhine, Drusus erects a military camp at Oberaden. 8 BC – Re-settlement of the Sicambri to the left bank of the Lower Rhine, under the control of Vetera. The military encampment in Oberaden was abandoned. 1 BC – Around this time Roman military bases were erected along the Lippe. The most important of these bases was situated at Haltern. After the Battle of the Teutoburg Forest in the autumn of 9 AD the Romans pull back to the left bank of the Rhine. 69 AD – Revolt of the Batavi, resulting in Asciburgium and Vetera being destroyed. At Vetera, a decisive battle is waged in the year 70, which the Romans win. The legion's camp is re-built. 85 – Transfer of the garrison from Asciburgium to present-day Duisburg-Werthausen so as to secure the Rhine crossing and the mouth of the Ruhr. 110 – The Colonia Ulpia Traiana, near to present-day Xanten, receives Roman town rights. 275 – The Colonia Ulpia Traiana is extensively damaged by a Frankish attack. In its place arises the mighty fortress of Tricensimae. 407 – Under Caesar Honorius the Rhine boundary of the Western Roman Empire is given up. 420 – The first traces of a Frankish settlement in Duisburg have been shown to stem from the 5th century, in the area of the old market. It lay immediately on the bank of the Rhine, as it then flowed. 428 – Around this time, Chlodio assumed the leadership of the Salian Franks; he is the first historically-verifiable king. According to the accounts of Gregory of Tours he lived in a district called "Dispargium" (possibly Duisburg or a castle on the Flanders Maas). 556 – Beginning of the struggle between Franks and Saxons
Early Middle Ages
695 – At the end of the 7th century, Christian missionaries from France are active in the neighbouring districts of the Frankish Bructeri. A wave of Saxon settlers certainly halted the religious conversion. The story of the failed mission is reflected in the Golden Legend, in which the work of Black Ewald and Fair Ewald, who were engaged in missionary work in Aplerbeck, came to a violent end in 695. 740 – Assumed establishment of the Königshof in Duisburg. 775 – The army of the Franks under Charlemagne conquers the Sigiburg, as well as the Eresburg near Niedermarsberg a year later. They were laid out as Reichshofs. 796 – Liudger founds Werden Abbey. 863 – Normans over-winter on Bislich Island at Xanten and destroy the local church. 870 – At Essen Abbey, founded by the Saxon noble Altfrid, the abbey church is inaugurated. 880 – Normans sack Birten. 883 – Regino von Prüm reports that Normans are over-wintering in the oppidum diusburh (Duisburg) having conquered it. The Burg Broich in Mülheim an der Ruhr is erected, probably as a reaction to these repeated Viking raids. It also guards the ford across the Ruhr by the Hellweg. 928 – King Henry I spends Easter in Dortmund. 929 – Reich synod in Duisburg. Between 922 and 1016, 18 residences in Duisburg by the King are mentioned in documents. 938 – King Otto I holds an imperial council (Hoftag) in Steele. 941 – Otto I (the Great) stays for the first time in Dortmund. A few years later. he also celebrates Easter in the Rhineland Palatinate. The common usage as pfalz underlines their importance. The Hellweg is an important connecting road of the Ottonischen kingdom. Along this trade route lie Dortmund and other old towns of the Ruhr, such as Duisburg and Essen. The Königshof in Duisburg is extended to a Königspfalz. 971 – Mathilde, granddaughter of Otto I becomes abbess of Essen Abbey. 978 – At a Reichsversammlung (Reich assembly) in Dortmund, in the presence of Ottos II, the decision was made to campaign against the Franks. 992 – On 7 May, the young Otto III receives ambassadors of the West Frankish king in Duisburg.Reg. Imp. II/3 Nr. 1059 und 1059a 993 – Reich Assembly of Otto III in Dortmund. Among other matters, the dispute between Bishop Dodo von Münster and Mettelen Abbey is decided in favour of the monastery.Ferdinand Frensdorff: Dortmunder Statuten und Urtheile. Halle a. S. : Verl. d. Buchhandl. d. Waisenhauses. 1882. S. X
High Middle Ages 1000 – Initial stages of the construction of churches in the romanesque style, like for example the Stiepeler Dorfkirche or the St.-Vinzentius-Kirche. 1002 – Henry II receives homage in Duisburg from bishops of Lorraine and the archbishop of Liege. 1005 – Synod of King Henry II in Dortmund. 1012 – Sophia, daughter of Otto II becomes abbottess of the Essen Stift. 1033 – The Benedictine Abbey in Werden is awarded rights over shipping on the Ruhr by King Conrad II - for the stretch from Werden to its mouth, 1041 – Essen receives rights to a market. 1073 – Under Essen abbess, , the parish chapel is erected on the Stoppenberg. In the 12th century it becomes the abbey church of a convent of Premonstratensians. 1122 – Count Gottfried of Cappenberg founds the first Premonstratensian foundation in the German-speaking lands, the Cappenberg Abbey in Selm. Furthermore, he gives over his castle and his fortune to the young order. Gottfried thereby becomes the last of the mighty counts of Cappenberg. His younger brother Otto of Cappenberg was godfather of Frederick I of Staufen. In 1155, Otto received as a gift from the recently crowned king the famous Cappenberg bust reliquary, a reliquary in the form of a bust of Frederick. 1123 – Kamp Abbey becomes the first Cistercian monastery in the German-speaking area. 1145 – The Knights Hospitallers opens its first foundation on German soil, by the walls of Duisburg, and builds the Marienkirche (church) there. 1152–1154 – A few months after his election to King, Frederick I of Staufen (Barbarossa) convenes a council (Hoftag) in Dortmund. But two years later, he and his retinue convene in the Palatinate. On both occasions, the mighty Duke of Saxony, Henry the Lion, is also present. 1160 – The County of Mark comes into being as a result of the division of the inheritance of the Count von Berg. 1173 – Emperor Frederick Barbarossa grants Duisburg the right to hold two fortnightly cloth fairs annually. 1199 – Completion of the Isenburg at Hattingen as the new power centre of the County of Isenberg an der Ruhr. 1200 – In Dortmund, large town walls are erected around the town. Its course is still retained in the inner city in the form of an embankment ("Wälle"). 1225 – Murder of the archbishop of Cologne, Engelbert I of Cologne, by Frederick of Isenberg. Frederick is executed, the larger part of the Grafschaft Isenberg an der Ruhr falls to his relative, the Count von der Mark. The Isenburg and the castle and town of Nienbrügge are razed. The Isenbergers had to accommodate themselves to the County of Limburg. 1225–1226 Settlers from Nienbrügge were settled in Ham between the Ahse and Lippe rivers by Count Adolphus of the Mark and received town rights from him in 1226. The old designation of Ham, a tongue of land between two rivers, becomes the name of the town, Hamm. 1228 – The Archbishop of Cologne takes over the Vest Recklinghausen. 1240 – The Dortmund Council obtained a house on the Markt vom Grafen von Dortmund. For centuries it was the Rathaus of the Reichsstadt.