Complex sentence: Arriving at Magnesia, however, the Company was informed of a terrible event: the local population, with its captain Ataliote at the head and with the support of the Alans, had beheaded the garrison and stolen its treasure.
Split into simpler sentences: Arriving at Magnesia, however, the Company was informed of a terrible event. The local population, with its captain Ataliote at the head and with the support of the Alans, had beheaded the garrison and stolen its treasure.