Complex sentence: The end result was that Aurelian established a new province of Dacia, "Dacia Aureliana" with its capital at "Serdica" previously belonging to Lower Moesia, with at least a proportion of the Romanized population settling in the new province south of the Danube.
Split into simpler sentences: The end result was that Aurelian established a new province of Dacia called Dacia Aureliana with its capital at Serdica, previously belonging to Lower Moesia. A portion of the Romanized population settled in the new province south of the Danube.