Complex sentence: Adalbert I (c.820--886), margrave of Tuscany from about 847, was the son of Margrave Boniface II, who had been despoiled of his fiefs by the Emperor Lothair I, and successor of his elder brother Aganus.
Split into simpler sentences: Adalbert I (c.820--886) was the margrave of Tuscany from about 847. He was the son of Margrave Boniface II, who had been despoiled of his fiefs by the Emperor Lothair I, and successor of his elder brother Aganus.