Kaesong

City · c. 911 CE · in Central Asia

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

Goryeo (918–1392 CE): Dynasty founded by Wang Geon with its capital at Kaesong; the name Korea derives from it.
Song dynasty (960–1279 CE): Founded by Zhao Kuangyin with its capital at Kaifeng, the Song saw a commercial revolution, paper money and advances in printing and science.
Silla (c. 57 BCE – c. 935 CE): Kingdom with its capital at Gyeongju, traditionally founded in 57 BCE, that unified most of Korea in the 7th century.
Jeonju (c. 892 CE): Capital of Hubaekje (892–935).
Kana (c. 900 CE): From simplified Chinese characters the Japanese developed the syllabic kana, hiragana and katakana; with kanji they still make up written Japanese.
Taiyuan (c. 936 CE): Capital of Later Jin (936–946), Northern Han (960–979).
Kaifeng (c. 951 CE): Capital of Later Zhou (951–960).
Balhae (698–926 CE): Kingdom founded by the former Goguryeo general Dae Jo-yeong in Manchuria and northern Korea.