Contemporary written sources about Mindaugas are very scarce.
Much what is known about his reign is obtained from the Livonian Rhymed Chronicle and the Hypatian Codex.
Both of these chronicles were produced by enemies of Lithuania and thus have anti-Lithuanian bias, particularly the Hypatian Codex.
They are also incomplete: both of them lack dates and locations even for the most important events.
For example, the Livonian Rhymed Chronicle devoted 125 poetry lines to Mindaugas's coronation, but failed to mention either the date or the location.
Other important sources are the papal bulls regarding baptism and coronation of Mindaugas.
The Lithuanians did not produce any surviving records themselves, except for a series of acts granting lands to the Livonian Order, but their authenticity is disputed.
Due to lack of sources, some important questions regarding Mindaugas and his reign cannot be answered.

Because written sources covering the era are scarce, Mindaugas's  origins and family tree have not been conclusively established.
The Bychowiec Chronicles, dating from the 16th and 17th centuries, have been discredited in this regard, since they assert an ancestry from the Palemonids, a noble family said to have originated within the Roman Empire.
His year of birth, sometimes given as c. 1200, is at other times left as a question mark.
His father is mentioned in the Livonian Rhymed Chronicle as a powerful duke (ein kunic grôß), but is not named; later chronicles give his name as Ryngold.
Dausprungas, mentioned in the text of a 1219 treaty, is presumed to have been his brother, and Dausprungas' sons Tautvilas and Gedvydas his nephews.
He is thought to have had two sisters, one married to Vykintas and another to Daniel of Halych.
Vykintas and his son Treniota played major roles in later power struggles.
Mindaugas had at least two wives, Morta and Morta's sister, whose name is unknown, and possibly an earlier wife; her existence is presumed because two children – a son named Vaišvilkas and an unnamed daughter married to Svarn in 1255 – were already leading independent lives when Morta's children were still young.
In addition to Vaišvilkas and his sister, two sons, Ruklys and Rupeikis, are mentioned in written sources.
The latter two were assassinated along with Mindaugas.
Information on his sons is limited and historians continue to discuss their number.
He may have had two other sons whose names were later conflated by scribes into Ruklys and Rupeikis.

In the 13th century Lithuania had little contact with foreign lands.
Lithuanian names sounded obscure and unfamiliar to various chroniclers, who altered them to sound more like names in their native language.
Mindaugas's name in historic texts was recorded in various distorted forms: Mindowe in Latin; Mindouwe, Myndow, Myndawe, Minde, and Mindaw in German; Mendog, Mondog, Mendoch, and Mindovg in Polish; and Mindovg, Mindog, and Mindowh in Rus', among others.
Since Rus' sources provide the most information about Mindaugas's life, they were judged the most reliable by linguists reconstructing his original Lithuanian name.
The most popular Rus' rendition was Mindovg, which can quite easily and naturally be reconstructed as Mindaugas or Mindaugis.
In 1909 the Lithuanian linguist Kazimieras Būga published a research paper supporting the suffix -as, which has since been widely accepted.
Mindaugas is an archaic disyllabic Lithuanian name, used before the Christianization of Lithuania, and consists of two components: min and daug.
Its etymology may be traced to "daug menąs" (much wisdom) or "daugio minimas" (much fame).
Contemporary written sources about Mindaugas are very scarce. Much what is known about his reign is obtained from the Livonian Rhymed Chronicle and the Hypatian Codex. Both of these chronicles were produced by enemies of Lithuania and thus have anti-Lithuanian bias, particularly the Hypatian Codex. They are also incomplete: both of them lack dates and locations even for the most important events. For example, the Livonian Rhymed Chronicle devoted 125 poetry lines to Mindaugas's coronation, but failed to mention either the date or the location. Other important sources are the papal bulls regarding baptism and coronation of Mindaugas. The Lithuanians did not produce any surviving records themselves, except for a series of acts granting lands to the Livonian Order, but their authenticity is disputed. Due to lack of sources, some important questions regarding Mindaugas and his reign cannot be answered.
Because written sources covering the era are scarce, Mindaugas's  origins and family tree have not been conclusively established. The Bychowiec Chronicles, dating from the 16th and 17th centuries, have been discredited in this regard, since they assert an ancestry from the Palemonids, a noble family said to have originated within the Roman Empire. His year of birth, sometimes given as c. 1200, is at other times left as a question mark. His father is mentioned in the Livonian Rhymed Chronicle as a powerful duke (ein kunic grôß), but is not named; later chronicles give his name as Ryngold. Dausprungas, mentioned in the text of a 1219 treaty, is presumed to have been his brother, and Dausprungas' sons Tautvilas and Gedvydas his nephews. He is thought to have had two sisters, one married to Vykintas and another to Daniel of Halych. Vykintas and his son Treniota played major roles in later power struggles. Mindaugas had at least two wives, Morta and Morta's sister, whose name is unknown, and possibly an earlier wife; her existence is presumed because two children – a son named Vaišvilkas and an unnamed daughter married to Svarn in 1255 – were already leading independent lives when Morta's children were still young. In addition to Vaišvilkas and his sister, two sons, Ruklys and Rupeikis, are mentioned in written sources. The latter two were assassinated along with Mindaugas. Information on his sons is limited and historians continue to discuss their number. He may have had two other sons whose names were later conflated by scribes into Ruklys and Rupeikis.
In the 13th century Lithuania had little contact with foreign lands. Lithuanian names sounded obscure and unfamiliar to various chroniclers, who altered them to sound more like names in their native language. Mindaugas's name in historic texts was recorded in various distorted forms: Mindowe in Latin; Mindouwe, Myndow, Myndawe, Minde, and Mindaw in German; Mendog, Mondog, Mendoch, and Mindovg in Polish; and Mindovg, Mindog, and Mindowh in Rus', among others. Since Rus' sources provide the most information about Mindaugas's life, they were judged the most reliable by linguists reconstructing his original Lithuanian name. The most popular Rus' rendition was Mindovg, which can quite easily and naturally be reconstructed as Mindaugas or Mindaugis. In 1909 the Lithuanian linguist Kazimieras Būga published a research paper supporting the suffix -as, which has since been widely accepted. Mindaugas is an archaic disyllabic Lithuanian name, used before the Christianization of Lithuania, and consists of two components: min and daug. Its etymology may be traced to "daug menąs" (much wisdom) or "daugio minimas" (much fame).
Mindaugas