Complex sentence: In 938, the ascendant Khitan, having unified the steppes, founded the Liao Dynasty and made Youzhou one of four secondary capitals, renaming city Nanjing (南京) or the "Southern Capital".
Split into simpler sentences: In 938, the ascendant Khitan having unified the steppes founded the Liao Dynasty. It made Youzhou one of its four secondary capitals, renaming it Nanjing (南京) or the "Southern Capital".