What happened in 1266? — events across the world

West Asia

Outbreak of the Byzantine–Ottoman wars
1265–1479Anatolia
Around 1265, the first of a series of military conflicts broke out between the Byzantine Empire and the emerging Ottoman Empire over Anatolia. This clash initiated a war that lasted over two centuries, ultimately leading to the fall of the Byzantine Empire and the rise of the Ottoman Empire.
SourcesWikipedia ↗
Launch of the First Crusade
1095–1291Jerusalem
In November 1095, Pope Urban II officially called for Christians to take up arms and reconquer Jerusalem at the Council of Clermont, launching the First Crusade and inaugurating a series of crusades that continued until 1291. The call promised spiritual rewards, and the success led to the establishment of four Crusader states in the Levant.
SourcesWikipedia ↗
Mongol invasions of Anatolia
1241–1335
The Mongol invasions of Anatolia began in 1241 with attacks on the city of Kâlin, culminating in the Battle of Köse Dağ in 1243. After the Seljuk defeat, the Sultanate of Rum submitted, and the Mongols assumed control over Anatolia. In 1255, following repeated Seljuk rebellions, Mongol forces swept through central and eastern Anatolia and stationed a garrison near Ankara. Their effective rule lasted until the collapse of the Ilkhanate in 1335.
SourcesWikipedia ↗

Battle of Benevento
1266
On 26 February 1266, the forces of Charles of Anjou defeated the army of King Manfred of Sicily near Benevento in Southern Italy. Manfred was killed in the battle, leading to Charles' conquest of the Kingdom of Sicily and the end of Hohenstaufen rule in the Italian Peninsula. The battle was part of the Guelph–Ghibelline conflict and was regarded as a crusade by the Papacy.
SourcesWikipedia ↗
Second Barons' War
1264–1267London
In 1264, the Second Barons' War broke out in England. A coalition of barons led by Simon de Montfort, Earl of Leicester, rose against King Henry III, seeking to compel the king to rule through a council of barons rather than his favourites. In 1265, de Montfort was killed at the Battle of Evesham, and the war ended in 1267 with the barons' surrender.
SourcesWikipedia ↗
Signing of the Treaty of Perth
1266Perth
On 2 July 1266, Scotland and Norway signed the Treaty of Perth, ending the military conflict over the sovereignty of the Hebrides and the Isle of Man. Norway ceded the islands to Scotland.
SourcesWikipedia ↗

Mongol invasions and conquests
1206–1337Karakorum, Mongol Empire capital
After the founding of the Mongol Empire in the early 13th century, Genghis Khan and his descendants launched a series of expansion wars across Eurasia, creating the largest contiguous land empire in history within a century and profoundly reshaping the political landscape of Eurasia.
SourcesWikipedia ↗

Mongol conquest of China begins
1205–1279Western Xia
In the early 13th century, the Mongol Empire under Genghis Khan initiated small-scale raids into Western Xia in 1205 and 1207, marking the beginning of a decades-long conquest of China. The conflict later escalated into full-scale campaigns against various Chinese dynasties.
SourcesWikipedia ↗

These are known only to the century, not to the year. They are listed separately so a rough date is never mistaken for an exact one.