Complex sentence: Sima Guang (17 November 1019--11 October 1086), courtesy name Junshi, was a high-ranking Song dynasty scholar-official and historian who authored the monumental history book "Zizhi Tongjian".
Split into simpler sentences: Sima Guang (17 November 1019--11 October 1086), courtesy name Junshi, was a Chinese historian, writer, and politician. He was a high-ranking Song dynasty scholar-official and historian who authored the monumental history book "Zizhi Tongjian".