Complex sentence: After his graduation from SOAS, Salibi joined AUB first as bibliographer of the Arab Studies Program and then as a professor in the department of History and Archaeology where he joined other famous historians such as Nicholas Ziadeh and Zein Zein.
Split into simpler sentences: After his graduation from SOAS, Salibi joined AUB first as bibliographer of the Arab Studies Program. He then became professor in the Department of History and Archaeology where he joined other prominent historians such as Nicholas Ziadeh and Zein Zein.