This text is taken from “The Might that was Assyria” by H.W.F. Saggs, ISBN 0-283-98961-0 – (hard) ISBN 0-283-98962-9 (soft)
Had Xenophon been in the area of Calah and Nineveh in more favourable circumstances, he might have learnt the identity of these ruins from local inhabitants. The destruction of the Assyrian empire did not wipe out its population. They were predominantly peasant farmers, and since Assyria contains some of the best wheat land in the Near East, descendants of the Assyrian peasants would, as opportunity permitted, build new villages over the old cities and carryon with agricultural life, remembering traditions of the former cities. After seven or eight centuries and various vicissitudes, these people became Christians. These Christians, and the Jewish communities scattered amongst them, not only kept alive the memory of the sites of their Assyrian predecessors but also combined them with traditions from the Bible. The Bible, indeed, came to be a powerful factor in keeping alive the memory of Assyria and particularly of Nineveh. Nineveh was at the centre of one of the most fascinating of the Old Testament legends, the story of the prophet Jonah who attempted in vain to escape the God-given duty of preaching to the great pagan capital. On part of the ruins of Nineveh there was a sacred mound, and this - probably originally an Assyrian temple - Christians and Jews came to identify with the spot where Jonah preached. A church was built on the site. When the Muslims conquered Mesopotamia in the seventh century A.D., they adopted the local traditions of the Christians and Jews amongst whom they lived, and Jonah (Yunus) became significant to Muslims no less than to Jews and Christians. A mosque replaced the church but retained - and retains to this day - the association with Jonah. The tenth-century Muslim geographer AI-Muqaddasi, describing the Mosul district, wrote: 'Here God forgave the people of Jonah. Does (the district) not contain the mosque of Jonah, at Tell Taubah [Repentance Hill], to which seven visits are said to be equal to a pilgrimage?' Another Muslim visitor to Mosul in the same century, Ibn Hawqal, spoke of the fertile land at Ninaway [Nineveh], where the prophet Jonah was buried.
Of course, this is a secular document and so they use the term "legend", none the less this is additional documentation that Johah existed and visited Nineveh.