Genghis in 1209 undertakes his campaign to actually conquer Western Xia.

Li Anquan requests aid from the Jin dynasty, but the new Prince Shao of Wei refuses to send aid.

After defeating a force led by Kao Liang-Hui outside Wulahai, Genghis captures the city and pushes up along the Yellow River, defeating several cities as he went, until he reached the fortress Kiemen which guarded the only pass through the Helan Mountains to the capital, Yinchuan.

Containing an army of up to seventy thousand plus fifty thousand reinforcements, the fortress proves too difficult to capture, and after a two-month standoff the Mongols feign a retreat, luring the garrison, led by Wei-ming Ling-kung, out onto the field where it is easily destroyed.

Genghis, his path now open, advances to the capital.

Yinchuan, well fortified, holds about one hundred and fifty thousand soldiers, nearly twice the size of the Mongol army.

This being the one of the Mongols’ first endeavors in siege warfare, they lack the proper equipment and experience to take the city.

They arrive at the city in May, but by October are still unsuccessful at breaking through.

Genghis attempts to flood the capital by diverting the river and its network of irrigation canals into the city.

Construction begins on Magdeburg’s Gothic-style cathedral after the entire original cathedral of St. Maurice had been destroyed on Good Friday in 1207 by a city fire.

All but the southern wing of the cloister had burned down.

Archbishop Albrecht II von Kefernburg had decided to pull down the remaining walls and construct a completely new cathedral, against some opposition of the people in Magdeburg.

Only the south wall of the cloister is still standing.

The archbishop, having traveled in Italy and France, has decided to construct the new cathedral modeled upon the Gothic architecture that had intrigued him in France.

The French style is completely unknown in Germany, and the hired craftsmen only gradually master it.

The construction of the choir starts in 1209, only two years after the fire that had destroyed the previous church, but this choir is still in a very Romanesque style, initially still using Romanesque groin vaults, combined with a gothic center stone, which however is not needed for Romanesque groin vaults.

The newly minted prince’s uncle, the marshal Geoffrey of Villehardouin, probably starts writing his sober, if biased, Histoire de l'empire de Constantinople, in which he describes the “crusade” by the Franks and their Venetian allies against the Greek empire. (Villehardouin's eyewitness account, usually known as the Conquête de Constantinople [“Conquest of Constantinople”], is the first original prose history written in French by a serious writer. His achievement, though unfinished at his death a few years later, is remarkable because neither in style nor form had he had any models on which to base his work; his Latin predecessors were probably unknown to him at first hand.)

The emperor of Nicaea forces Latin emperor Henry to sign a two-year armistice following a failed attempt by the Latins to invade Asia Minor.

The Latins then conclude a secret alliance with …

…the Seljuqs, who fight Nicaea from 1209.

Making Lahore his capital, Aibak consolidates his control over North India through …

…an administrative hold over Delhi.

Aibak also initiates the construction of Delhi's earliest Muslim monuments, the Quwwat-ul-Islam mosque and the Qutub Minar.

Geoffrey de Villehardouin manages to take the place of William’s replacement, his nephew Hugo, when William leaves for France in 1209, and he is recognized as Prince of Achaea.

Muhammad al-Nasir crosses the Strait of Gibraltar in 1209 with a powerful war machine, invading Christian territory and capturing the stronghold of the Calatrava Knights (now known as the Order of Salvatierra) in Salvatierra.

After this, the threat is so great for the Iberian Christian kingdoms that Pope Innocent III calls European knights to a crusade.

Roger of Wendover wrote shortly after the foundation of the University of Cambridge that it could trace its origins to a crime committed in 1209.

Although not always a reliable source, the detail given in his contemporaneous writings lends them credence.

Two Oxford scholars, convicted of the murder or manslaughter of a woman, had been hanged by the town authorities with the assent of King John.

The University of Oxford had gone into voluntary suspension in protest at the hanging, and scholars migrated to a number of other locations, including the preexisting school at Cambridge (Cambridge had been recorded in 1201 as a “school” rather than as a university when John Grim held the office of Master there).

These exile Oxford scholars (postgraduate researchers by present day terminology) in 1209 start Cambridge’s life as a university.