Henry is an able military leader.

Duke Burchard II of Swabia had soon sworn fealty to the new King, but Duke Arnulf of Bavaria does not submit until Henry defeats him in two campaigns in 921.

Last, Henry besieges his residence at Ratisbon (Regensburg) and forces Arnulf into submission.

Simeon's forces appear before Constantinople in 921, when they demand the deposition of Romanos and capture Adrianople.

The Bulgarians have reached and crossed the Dardanelles to lay siege on the town of Lampsacus.

Magyars invade Germany and Italy in 921.

Although a sizable force is routed near Bleiburg in the Bavarian March of Carinthia by Eberhard and the Count of Meran and another group is routed by Liutfried, count of Elsass (Alsace), the Magyars repeatedly raid Germany.

Bertha, the eldest daughter of Berengar I of Italy, had become abbess of San Salvatore in Brescia, where her aunt had once been a nun, by 915.

In that year, the following year, and in 917, Berengar had endowed her monastery with three privileges to build or man fortifications.

Berengar retreats to Verona and has to watch, sidelined, as the Magyars pillage the country.

Berengar’s younger daughter, Gisela, had married Adalbert I of Ivrea as early as 898 (and no later than 910), but this had failed to spark an alliance with the Anscarids.

She was dead by 913, when Adalbert remarried.

Adalbert, one of Berengar's earliest internal enemies after the defeat of Louis of Provence, has called on Hugh of Arles between 917 and 920 to take the Iron Crown.

Hugh had invaded Italy, with his brother Boso, and advanced as far as Pavia, where Berengar had starved them into submission, but allowed them to pass out of Italy freely.

Dissatisfied with the emperor, who had ceased his policy of grants and family alliances in favor of paying Magyar mercenaries, several Italian nobles—led by Adalbert and many of the bishops—invite Rudolph II of Upper Burgundy, king from 912, to take the Italian throne in 921.

Moreover, his own grandson, Berengar of Ivrea, rises up against him, incited by Rudolph.

Mahdia is made the capital city of Ifriqiya upon its founded by the Fatimids under the Caliph Abdallah al-Mahdi in 921.

It has been chosen as the capital because of its proximity to the sea, and the promontory on which an important military settlement had been since the time of the Phoenicians: the city was classically known as Ruspae and later as Henchir Sbia or just Sbia.

The Mahdia shipwreck—a sunken ship found off Mahdia's shore, containing Greek art treasures—is dated to about 80 BCE, the early part of Roman rule in this region.

Isaac Israeli ben Solomon serves as court physician to the Fatimid caliph, writing medical treatises in Arabic.

He is an Egyptian-born Jew, he is also a Neoplatonic philosopher.

The second of the Fatimids’ two campaigns into Egypt, led by al-Mahdi’s son al-Qaim, fails in 1921, as had the first, in 915, in the face of stiff resistance by the Abbasids.