Mahdia

City · c. 911 CE · in Europe

Capital of Fatimid Caliphate (911–948), Zirid dynasty (1057–1148), Kingdom of Africa (1152–1160).

Kaesong (c. 911 CE): Capital of Taebong (911–918), Goryeo (922–1392).
Lugo (c. 911 CE): Capital of Kingdom of Galicia (911–1125).
Changsha (c. 911 CE): Capital of Southern Chu (911–951).
Regensburg (c. 911 CE): Capital of Kingdom of Germany (911–961), Holy Roman Empire (1594–1806), Holy Roman Empire Minor States (1594–1806), and 1 more.
Hangzhou (c. 911 CE): Capital of Wuyue (911–978).
Beijing (c. 911 CE): Capital of Yan Kingdom (911–914), Ming Dynasty (1375–1644), Empire of China (1916–1916), and 2 more.
Tui (c. 911 CE): Capital of Kingdom of Galicia (911–1125).
Fengxiang District (c. 911 CE): Capital of Qi Kingdom (911–924).
Bratislava (907 CE): Capital of Kingdom of Hungary (1526–1546).
Shangjing Linhuangfu (c. 916 CE): Capital of Liao Dynasty (916–1125).

Around the same time and place

Reconquista (718–1492 CE): Centuries-long series of campaigns by Christian kingdoms to take the Iberian Peninsula from Muslim rule, ending with the fall of Granada in 1492.
Olbia (c. 866 CE): Capital of Giudicato of Gallura (866–1209).
Porto Torres (c. 866 CE): Capital of Giudicato of Logudoro (866–1259).
Burgos (884 CE): Capital of Kingdom of Castile (1065–1235).
Hungarian conquest (c. 895 CE): Magyar tribes led by Árpád crossed the Carpathians and settled the Pannonian Basin, laying the foundation of the Hungarian state.
Székesfehérvár (c. 900 CE): Capital of Principality of Hungary (900–999), Kingdom of Hungary (1000–1543).
Andorra la Vella (900 CE): Capital of Principality of Andorra (1815–today).
Fatimid Caliphate founded (909 CE): The Ismaili Shia leader Abdallah al-Mahdi proclaimed himself caliph in Ifriqiya, founding the Fatimid Caliphate, which later conquered Egypt.