|Centuries:||12th century – 13th century – 14th century|
|Decades:||1220s 1230s 1240s – 1250s – 1260s 1270s 1280s|
|Years:||1250 1251 1252 1253 1254 1255 1256 1257 1258 1259|
|Categories:||Births – Deaths – Architecture
Establishments – Disestablishments
The 1250s decade ran from January 1, 1250, to December 31, 1259.
Events and trends 
The decade was perhaps most dominated by the Mongols, who under the leadership of Möngke Khan continued their rapid expansion throughout Asia both to the east and west of their home territories. The Mongols destroyed the Kingdom of Dali in Laos, and captured the Goryeo kingdom in Korea, eastern Galicia in Europe, Anatolia in Turkey, and the Islamic center of Baghdad, where tens or hundreds of thousands were killed as the city was burned to the ground. In Thailand the Lannathai kingdom was founded. In Japan, a new sect of Buddhism was formed, while in Korea the carving of Buddhist scriptures on 81,000 wooden blocks was completed.
Europe noted several important cultural milestones, including the completion of several important cathedrals and the beginning of construction of others, as well as the founding of the Collège de Sorbonne at the University of Paris. Significant political developments in Europe included the lack of a Holy Roman Emperor for most of the decade, further erosion of the power of the monarchy in England and Portugal, the end of the failed Seventh Crusade in Egypt, and the expulsion of the Jews from France and the Moors from Portugal. In religion, a papal bull authorized the use of torture in the Medieval Inquisition, and the Roman Catholic Church clarified the concept of purgatory. Several important modern cities, including Stockholm and Lviv, were founded in the 1250s.
One of the largest volcanic eruptions of the Holocene epoch is thought to have occurred circa January 1258, with ice cores pointing to a tropical location such as El Chichón, Mexico or possibly Quilotoa, Ecuador. The aftermath may have led to climatic anomalies in rainfall, effects on agriculture, as well as famine and epidemic disease across Europe.
War and politics 
Mongol Empire 
- 1251 – Möngke Khan is elected as the fourth khan of the Mongol Empire.
- 1253 – Galicia becomes a vassal state to the expanding Mongol Empire.
- 1253 – The Mongol Empire launches attacks on the Muslim cities of Baghdad and Cairo.
- 1253 – The Mongol Empire destroys the Kingdom of Dali (Yunnan) in Laos and incorporates the region into their empire.
- 1253 – Kublai Khan introduces the baisha xiyue song and dance suite to the music of Yunnan.
- 1255 – Hulagu Khan is dispatched by his brother Möngke Khan to destroy the remaining Muslim states in southwestern Asia.
- 1256 – October – Mongol commander Baiju (operating under Hulagu Khan's command) leads his forces in a victory over Kay Ka'us II of the Sultanate of Rüm, thereby capturing Anatolia.
- 1256 – December 15 – Hulagu Khan captures and destroys the Hashshashin stronghold at Alamut in present-day Iran.
- 1256 – Hulagu Khan establishes the Ilkhanate dynasty of Persia, which will become one of four main divisions of the Mongol Empire.
- 1258 – February 13 – The Hulagu Khan's Mongol forces overrun Baghdad, then the leading center of Islamic culture and learning, burning it to the ground and killing as many as 800,000 citizens.
- 1259 – The Goryeo kingdom in Korea surrenders to invading Mongol] forces.
- 1259 – Second Mongol Golden Horde raid against Poland, led by Nogai Khan.
- 1250 – December 13 – Frederick II, Holy Roman Emperor, dies, beginning a 23-year-long interregnum known as the great interregnum. Frederick II is the last Holy Roman Emperor of the Hohenstaufen dynasty; after the interregnum, the empire passes to the Habsburgs. The Lombard League dissolves upon the death of Frederick II, its member states' nemesis.
- 1250 – King Afonso III of Portugal captures the Algarve from the Moors, thus completing the expulsion of the Moors from Portugal.
- 1251 – Andrew of Longumeau, dispatched two years earlier by King Louis IX of France as an ambassador to the Mongols, returns to his king with reports from the Mongols and Tartary; his mission is considered a failure.
- 1253 – King Henry III of England meets with English nobles and church leaders to reaffirm the validity of the Magna Carta.
- 1254 – King Louis IX of France, having exhausted his funds and being needed at home, abandons the Seventh Crusade (which he had conducted first in Egypt and then Syria) and returns to France.
- 1254 – King Louis IX of France expels all Jews from France.
- 1254 – King Afonso III of Portugal holds the first session of the Cortes (Portugal's general assembly composed of nobles, members of the middle class, and representatives from all municipalities) in Leiria.
- 1254 – In England, an important step in the evolution of the Parliament and Peerage occurs, as lesser barons are replaced on the King's Council by elected representatives from shires and cities.
- 1255 – May – William of Rubruck from Constantinople returns to Cyprus from his missionary journey to convert the Tatars of central and eastern Asia, his efforts having been unsuccessful.
- 1258 – King Henry III of England is forced by seven powerful barons to accept the Provisions of Oxford, effectively ending the absolute monarchy in England by requiring the calling of a parliament.
- 1259 – September – The Empire of Nicaea defeats the Principality of Achaea at the Battle of Pelagonia, ensuring the eventual reconquest of Constantinople in 1261.
- 1259 – December 4 – Kings Louis IX of France and Henry III of England agree to the Treaty of Paris, in which Henry renounces his claims to French-controlled territory on continental Europe (including Normandy) in exchange for Louis withdrawing his support for English rebels.
- 1259 – The German cities of Lübeck, Wismar, and Rostock enter into a pact to defend against pirates of the Baltic Sea, laying the groundwork for the Hanseatic League.
Asia and Africa 
- 1250 – The Bahri dynasty of Mamluks seize power in Egypt.
- 1259 – Lannathai, a kingdom in the north of Thailand, is founded by King Mangrai.
Science and literature 
- 1250 – Albertus Magnus isolates the element arsenic. He also first uses the word oriole to describe a type of bird (most likely the golden oriole of Great Britain).
- 1254 – The classic Japanese text Kokin Chomonjo is completed.
- 1257 – Matthew Paris, English historian, personally interviews King Henry III of England for a week straight while compiling his major work of English history, Chronica Majora.
Art and architecture 
- 1250 – The Rialto Bridge in Venice, Italy is converted from a pontoon bridge to a permanent, raised wooden structure.
- 1253 – The Basilica of San Francesco, the earliest important structure in the Italian Gothic style of architecture, is completed in Assisi, Italy.
- 1254 – The Horses of Saint Mark, once supposed to have adorned the Arch of Trajan in ancient Rome, are installed at Saint Mark's Basilica in Venice.
- 1254 – Construction is begun on the Cathedral of Saint Martin in Utrecht.
- 1255 – The Gothic cathedral Cathédrale Saint-Étienne de Bourges at Bourges, France, is completed. It is now a UNESCO World Heritage Site.
- 1259 – The famous frescoes of the Boyana Church in Bulgaria are completed (the church and its murals are now a UNESCO World Heritage Site).
Cities and institutions 
- 1250 – University of Valladolid is founded in Spain.
- 1251 – The German city of Berlin, founded some fifty years earlier, receives its city charter.
- 1252 – The first European gold coins are minted in the Italian city of Florence, and are known as florins.
- 1252 – The Swedish city of Stockholm is founded by Birger Jarl.
- 1254 – The Danish city of Copenhagen receives its city charter.
- 1254 – The Swedish city of Malmö is founded.
- 1255 – The Portuguese capital is moved to Lisbon.
- 1255 – Königsberg (now Kaliningrad) is founded in Prussia.
- 1256 – The city of Lviv, in present-day Ukraine, is founded by Danylo King of Rus.
- 1257 – Robert de Sorbon founds the Collège de Sorbonne at Paris, giving a formal college (and still-common name) to the already existing University of Paris in France.
- 1251 – Carving of the Tripitaka Koreana, a collection of Buddhist scriptures recorded on some 81,000 wooden blocks, is completed.
- 1252 – May 15 – Pope Innocent IV issues the papal bull Ad exstirpanda, which authorizes the torture of heretics in the Medieval Inquisition. Torture quickly gains widespread usage across Catholic Europe.
- 1253 – April 28 – Nichiren, a Japanese Buddhist monk, declares his intention to preach the Lotus Sutra and Nam Myoho Renge Kyo as the true Buddhism, essentially founding the branch of Buddhism now known as Nichiren Buddhism.
- 1254 – The Catholic dogma of purgatory is clarified and so named by the Catholic Church.
- 1256 – April 13 – Pope Alexander IV issues a papal bull constituting the Order of Saint Augustine.
- 1254 – September 15 – Marco Polo, Venetian merchant and explorer (d. 1324)
- 1255 – July – Albert I of Germany, Holy Roman Emperor (d. 1308)
- 1258 – Osman I, founder of the Ottoman Empire (d. 1326)
- 1250 – December 13 – Frederick II, Holy Roman Emperor (b. 1194)
- 1250 – Leonardo of Pisa, better known as Fibonacci
- 1253 – September 22 – Dōgen Zenji, founder of the Sōtō school of Zen Buddhism in Japan and author of the Shōbōgenzō and other important works (b. 1200)
- 1254 – December 7 – Pope Innocent IV
- 1255 – Batu Khan, Mongol ruler and founder of the Blue Horde (b. c. 1205)
- 1256 – Felim mac Cathal Crobderg Ua Conchobair, King of Connacht