Complex sentence: Scylax and his companions sailed down the river to the east and the rising of the sun, till they reached the sea, whence they sailed westward through the Indian Ocean to the Red Sea, performing the whole voyage and returning in thirty months.
Split into simpler sentences: Scylax and his companions sailed down the river to the east and the rising of the sun, till they reached the sea. From whence they sailed westward through the Indian Ocean to the Red Sea, performing the whole voyage and returning in thirty months.