From BiblePortal Wikipedia

Morrish Bible Dictionary [1]

The Ninevites or Assyrians, as known in scripture and on the monuments, are judged to have belonged to the Semitic stock — the older inhabitants of the district having been expelled or destroyed. They would thus be allied in blood and in language to the Hebrews. They differed from the Babylonians who were a mixed race, partlyAccadian and partly Semitic.

The Accadians invented the cuneiform system of writing which was adopted by the Assyrians, and tablets have been found explaining Accadian words by Assyrian words. A learned Assyrian studied Accadian as a dead language, as Latin is now studied by educated people. The Assyrians were, however, a warlike people, and were not much given to literature and peaceful pursuits; yet various 'lesson books' have been discovered which show that literature was not altogether neglected.

The records give evidence of the great ferocity of the Assyrians, who were less humane than the Babylonians. They impaled some of their victims, burnt others, and they even flayed alive the king of Hamath. Their cruelty is alluded to in  Nahum 2:12; "The lion did tear in pieces enough for his whelps, and strangled for his lionesses, and filled his holes with prey, and his dens with ravin."

The greater part of the religious system of Babylon was transported into Assyria, though the Assyrians were less given to religious observances. They had, however, their ritual and their prayers. One of these is remarkable:

"Let the wind carry away the transgression I have committed,

Destroy my manifold wickedness like a garment.

O my God, seven times seven are my transgressions,

My transgressions are ever before me."

But excuses were made that the sins were those of ignorance:

"The transgression that I committed I knew not,

The sin that I sinned I knew not."

The whole (about 60 lines) was to be repeated ten times, and at the end is added, "For the tearful supplication of the heart let the glorious name of every god be invoked sixty-five times, and the heart shall have peace." — Assyria: its Princes, Priests, and People.

They had their temple, with its inner and outer courts, and a shrine to which only priests were admitted. A 'sea' of water was at its entrance, and winged bulls, called 'cherubs,' protected the place. They had their 'sabbath' and their sacrifices, principally the bullock, part of which was burnt on the altar, and part eaten by the offerer, or given to the priest. This appears to have been a counterfeit of the tabernacle and its service.

Holman Bible Dictionary [2]

 Luke 11:30 11:32 Jonah 3 Luke 4:26-27 Luke 7:9 Luke 11:31 Luke 17:15-18

International Standard Bible Encyclopedia [3]

nin´ḗ - vı̄ts ( Νινευ ( ρ Ο2 επ ) ῖται , Nineu ( e ) ı́tai ): Only in   Luke 11:30 . The parallel passage ( Matthew 12:41 ), with  Luke 11:32 , has the fuller form, "men of Nineveh," which gives the meaning.