Complex sentence: The Taifa of Arcos was a medieval taifa kingdom that existed in two periods; first from 1011 to 1068 when it was conquered by the Taifa of Seville, and secondly from 1143 to 1145 when it was finally conquered by the Almohads.
Split into simpler sentences: The Taifa of Arcos was a medieval taifa kingdom that existed in two periods; first from 1011 to 1068. It regained its independence from 1143 to 1145 when it was finally conquered by the Almohads.