Complex sentence: According to Gilbert-Charles Picard, the power of the wealthy family of Severianus, the "Sedatii", seems to be from trade and commerce, the "Sedatii" depended on the Loire river, and were known to have had interests in Ostia.
Split into simpler sentences: According to Gilbert-Charles Picard, the power of the wealthy family of Severianus (the "Sedatii") seems to be from trade and commerce. The "Sedatii" depended on the Loire river, and were known to have had interests in Ostia.