A coregency is the situation where a monarchical position (such as king, queen, emperor or empress), normally held by only a single person, is held by two.

Historical examples of this include the coregency of Frederick I of Austria

Frederick I of Austria (Habsburg)

Frederick the Handsome or the Fair , from the House of Habsburg, was Duke of Austria and Styria from 1308 as Frederick I as well as King of Germany from 1314 as Frederick III until his death.-Biography:He was the second son of King Albert I of Germany with his wife Elisabeth of...

 and Louis the Bavarian over the Kingdom of Germany

Kingdom of Germany

The Kingdom of Germany developed out of the eastern half of the former Carolingian Empire....

, and the coregency of William and Mary

William and Mary

The phrase William and Mary usually refers to the coregency over the Kingdoms of England, Scotland and Ireland, of King William III & II and Queen Mary II...

 over England (along with Wales

Wales

Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...

), Scotland, and Ireland. It was also found in Sparta

Sparta

Sparta or Lacedaemon, was a prominent city-state in ancient Greece, situated on the banks of the River Eurotas in Laconia, in south-eastern Peloponnese. It emerged as a political entity around the 10th century BC, when the invading Dorians subjugated the local, non-Dorian population. From c...

 with two Kings, San Marino

San Marino

San Marino, officially the Republic of San Marino , is a state situated on the Italian Peninsula on the eastern side of the Apennine Mountains. It is an enclave surrounded by Italy. Its size is just over with an estimated population of over 30,000. Its capital is the City of San Marino...

 with two Captains Regent, the ancient Roman Empire

Roman Empire

The Roman Empire was the post-Republican period of the ancient Roman civilization, characterised by an autocratic form of government and large territorial holdings in Europe and around the Mediterranean....

 (by determination of Hadrian

Hadrian

Hadrian , was Roman Emperor from 117 to 138. He is best known for building Hadrian's Wall, which marked the northern limit of Roman Britain. In Rome, he re-built the Pantheon and constructed the Temple of Venus and Roma. In addition to being emperor, Hadrian was a humanist and was philhellene in...

) and the Byzantine Empire

Byzantine Empire

The Byzantine Empire was the Eastern Roman Empire during the periods of Late Antiquity and the Middle Ages, centred on the capital of Constantinople. Known simply as the Roman Empire or Romania to its inhabitants and neighbours, the Empire was the direct continuation of the Ancient Roman State...

, Ancient Egypt

Ancient Egypt

Ancient Egypt was an ancient civilization of Northeastern Africa, concentrated along the lower reaches of the Nile River in what is now the modern country of Egypt. Egyptian civilization coalesced around 3150 BC with the political unification of Upper and Lower Egypt under the first pharaoh...

 and Nubia

Nubia

Nubia is a region along the Nile river, which is located in northern Sudan and southern Egypt.There were a number of small Nubian kingdoms throughout the Middle Ages, the last of which collapsed in 1504, when Nubia became divided between Egypt and the Sennar sultanate resulting in the Arabization...

, in these cases as a balance between King and Queen, male and female. Jure uxoris

Jure uxoris

Jure uxoris is a Latin term that means "by right of his wife" or "in right of a wife". It is commonly used to refer to a title held by a man whose wife holds it in her own right. In other words, he acquired the title simply by being her husband....

Kings in Kingdoms such as Spain

Spain

Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...

 and Portugal

Portugal

Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...

 can also be found (Ferdinand V and Isabella I of Castile

Isabella I of Castile

Isabella I was Queen of Castile and León. She and her husband Ferdinand II of Aragon brought stability to both kingdoms that became the basis for the unification of Spain. Later the two laid the foundations for the political unification of Spain under their grandson, Charles V, Holy Roman Emperor...

, Philip I

Philip I of Castile

Philip I , known as Philip the Handsome or the Fair, was the first Habsburg King of Castile...

 and Joanna of Castile

Joanna of Castile

Joanna , nicknamed Joanna the Mad , was the first queen regnant to reign over both the Crown of Castile and the Crown of Aragon , a union which evolved into modern Spain...

, Peter III

Peter III of Portugal

Peter III became King of the Kingdom of Portugal and the Algarves by the accession of his wife and niece Queen Maria I in 1777, and co-reigned alongside her until his death.-Biography:...

 and Maria I of Portugal

Maria I of Portugal

Maria I was Queen regnant of Portugal and the Algarves from 1777 until her death. Known as Maria the Pious , or Maria the Mad , she was the first undisputed Queen regnant of Portugal...

, etc.).

The city of Maastricht

Maastricht

Maastricht is situated on both sides of the Meuse river in the south-eastern part of the Netherlands, on the Belgian border and near the German border...

 was under the joint jurisdiction (parage

Parage

Parage may refer to:*Parage , a village in the Bačka Palanka municipality, in the Vojvodina province of Serbia*Paréage, a feudal institution that recognizes equality of rights and status between two rulers. Also, equality in the portions of an inheritance...

) of the duke of Brabant

Duchy of Brabant

The Duchy of Brabant was a historical region in the Low Countries. Its territory consisted essentially of the three modern-day Belgian provinces of Flemish Brabant, Walloon Brabant and Antwerp, the Brussels-Capital Region and most of the present-day Dutch province of North Brabant.The Flag of...

 and the prince-bishop of Liège. In 1648 it became a real condominium

Condominium (international law)

In international law, a condominium is a political territory in or over which two or more sovereign powers formally agree to share equally dominium and exercise their rights jointly, without dividing it up into 'national' zones.Although a condominium has always been...

 of two independent states, the Principality of Liège

Bishopric of Liège

The Bishopric of Liège or Prince-Bishopric of Liège was a state of the Holy Roman Empire in the Low Countries in present Belgium. It acquired its status as a prince-bishopric between 980 and 985 when Bishop Notger, who had been the bishop of Liege since 972, acquired the status of Prince-Bishop...

 and the republic of the United Provinces

Dutch Republic

The Dutch Republic — officially known as the Republic of the Seven United Netherlands , the Republic of the United Netherlands, or the Republic of the Seven United Provinces — was a republic in Europe existing from 1581 to 1795, preceding the Batavian Republic and ultimately...

. The coregency of the last was no longer held by a person but by the Estates-General of the Netherlands (until 1794).

A similar situation still exists today in Andorra

Andorra

Andorra , officially the Principality of Andorra , also called the Principality of the Valleys of Andorra, , is a small landlocked country in southwestern Europe, located in the eastern Pyrenees mountains and bordered by Spain and France. It is the sixth smallest nation in Europe having an area of...

, which has two Princes (the Bishop of Urgel and the President of France).

Another example is in Ancient Egypt

Ancient Egypt

Ancient Egypt was an ancient civilization of Northeastern Africa, concentrated along the lower reaches of the Nile River in what is now the modern country of Egypt. Egyptian civilization coalesced around 3150 BC with the political unification of Upper and Lower Egypt under the first pharaoh...

, mainly in the Middle Kingdom, the Pharaoh

Pharaoh

Pharaoh is a title used in many modern discussions of the ancient Egyptian rulers of all periods. The title originates in the term "pr-aa" which means "great house" and describes the royal palace...

 occasionally appointed his successor (often one of his sons) as coregent, or joint King, to ensure a smooth succession. The Pharaoh also did this when he was elderly or unable to rule his country on his own (such as the case of Thutmose III

Thutmose III

Thutmose III was the sixth Pharaoh of the Eighteenth Dynasty. During the first twenty-two years of Thutmose's reign he was co-regent with his stepmother, Hatshepsut, who was named the pharaoh...

 and Amenhotep II

Amenhotep II

Amenhotep II was the seventh Pharaoh of the 18th dynasty of Egypt. Amenhotep inherited a vast kingdom from his father Thutmose III, and held it by means of a few military campaigns in Syria; however, he fought much less than his father, and his reign saw the effective cessation of hostilities...

 or Amenemhat I

Amenemhat I

Amenemhat I, also Amenemhet I, was the first ruler of the Twelfth Dynasty . He ruled from 1991 BC to 1962 BC...

 and Senusret I

Senusret I

Senusret I was the second pharaoh of the Twelfth Dynasty of Egypt. He ruled from 1971 BC to 1926 BC, and was one of the most powerful kings of this Dynasty. He was the son of Amenemhat I and his wife Nefertitanen. His wife and sister was Neferu. She was also the mother of the successor Amenemhat II...

). The existence of the practice makes establishing firm dates in Egyptian chronology

Egyptian chronology

The creation of a reliable chronology of Ancient Egypt is a task fraught with problems. While the overwhelming majority of Egyptologists agree on the outline and many of the details of a common chronology, disagreements either individually or in groups have resulted in a variety of dates offered...

 more of a challenge, as the lengths of coregencies are often uncertain and complicate the use of accepted regnal lengths to establish dates. Some of the Queens of Egypt rose to a status of equal to the God-Kings, becoming co-rulers and / or at least as important in religious affairs, and were even portrayed with the same size as their male consort and even with the same size as the other Gods of Egypt. Such were the cases of Hatshepsut

Hatshepsut

Hatshepsut also Hatchepsut; meaning Foremost of Noble Ladies;1508–1458 BC) was the fifth pharaoh of the eighteenth dynasty of Ancient Egypt...

, Nefertiti

Nefertiti

Nefertiti was the Great Royal Wife of the Egyptian Pharaoh Akhenaten. Nefertiti and her husband were known for a religious revolution, in which they started to worship one god only...

, Nefertari

Nefertari

Nefertari also known as Nefertari Merytmut was one of the Great Royal Wives of Ramesses the Great. Nefertari means 'Beautiful Companion' and Meritmut means 'Beloved of [the Goddess] Mut'. She is one of the best known Egyptian queens, next to Cleopatra, Nefertiti and Hatshepsut...

 and the Nubian Egyptian Queens. In the Ptolemaic Dynasty

Ptolemaic dynasty

The Ptolemaic dynasty, was a Macedonian Greek royal family which ruled the Ptolemaic Empire in Egypt during the Hellenistic period. Their rule lasted for 275 years, from 305 BC to 30 BC...

 women finally rose to become equal co-rulers with men and even challenging them in order to become their respective consorts. This was due to a progressive improvement of the already high status of women in the Egyptian society

Women in Egypt

-Women in Ancient Egypt:From the earliest preserved archaeological records, women in Egypt have been thought to be considered nearly equal to men in Egyptian society, regardless of marital status. Women were stated lower than men when it came to a higher leader in the Egyptian hierarchy counting...

, as well as to the religious principle of balance (Maat

Maat

Maat is a naval rank of the German navy equivalent to the army rank of Unteroffizier. A Maat is considered the equivalent of a junior Petty Officer in the navies of many other nations....

) between male and female. In Nubia

Nubia

Nubia is a region along the Nile river, which is located in northern Sudan and southern Egypt.There were a number of small Nubian kingdoms throughout the Middle Ages, the last of which collapsed in 1504, when Nubia became divided between Egypt and the Sennar sultanate resulting in the Arabization...

, Queens like Amanishakheto

Amanishakheto

Amanishakheto was a Kandake of Nubia. She seems to have reigned from 10 BC to 1 AD, although most dates of Nubian history before the Middle Ages are very uncertain.In Meroitic hieroglyphs her name is written as Amanikasheto...

 and Amanitore

Amanitore

Amanitore was a Nubian Kandake of the ancient Kushitic Kingdom of Meroë, which also is referred to as Nubia in many ancient sources. An alternate spelling is Kandace, Kandake, or Kentake. In Egyptian hieroglyphics the throne name of Amanitore reads as Merkare...

 were crowned alongside Kings at Dangeil and had both their pyramids

Nubian pyramids

Nubian pyramids are pyramids that were built by the rulers of the Kushite and Egyptian kingdoms. Prior to the Kushites building these pyramids , there had been no pyramid construction in Egypt and the Nile Valley for more than 500 years.The area of the Nile valley known as Nubia, which lies within...

 at Meroë

Meroë

Meroë Meroitic: Medewi or Bedewi; Arabic: and Meruwi) is an ancient city on the east bank of the Nile about 6 km north-east of the Kabushiya station near Shendi, Sudan, approximately 200 km north-east of Khartoum. Near the site are a group of villages called Bagrawiyah...

 with the same height and side by side, and exerced power at the same level, even commanding armies. In Ethiopia

Ethiopia

Ethiopia , officially known as the Federal Democratic Republic of Ethiopia, is a country located in the Horn of Africa. It is the second-most populous nation in Africa, with over 82 million inhabitants, and the tenth-largest by area, occupying 1,100,000 km2...

, Kandake

Kandake

Kandake or Kentake, also Candace, was the title for queens and queen mothers of the ancient African Kingdom of Kush, also known as Nubia and Ethiopia....

s also reached and hold this or a similar status.

In the book The Mysterious Numbers of the Hebrew Kings, Edwin R. Thiele

Edwin R. Thiele

Edwin R. Thiele was an American missionary in China, an editor, archaeologist, writer, and Old Testament professor. He is best known for his chronological studies of the Hebrew kingdom period.- Biography :...

 proposed coregency as a possible explanation for discrepancies in the dates given in the Hebrew Bible

Hebrew Bible

The Hebrew Bible is a term used by biblical scholars outside of Judaism to refer to the Tanakh , a canonical collection of Jewish texts, and the common textual antecedent of the several canonical editions of the Christian Old Testament...

 for the reigns of the kings of Israel

Israel

The State of Israel is a parliamentary republic located in the Middle East, along the eastern shore of the Mediterranean Sea...

 and Judah

Kingdom of Judah

The Kingdom of Judah was a Jewish state established in the Southern Levant during the Iron Age. It is often referred to as the "Southern Kingdom" to distinguish it from the northern Kingdom of Israel....

. At least one coregency is explicitly documented in the Bible: the coronation of King Solomon occurred before the death of his father David

David

David was the second king of the united Kingdom of Israel according to the Hebrew Bible and, according to the Gospels of Matthew and Luke, an ancestor of Jesus Christ through both Saint Joseph and Mary...

. Some Kings of Egypt, specially during the Twelfth Dynasty, also practised this custom, by associating their own sons in order to both prepare them for the office and prevent anyone else from usurping the throne, specially during its earlier days.