Zenaide Ragozin, The Rise and Fall of the Assyrian Empire. They lost there empire to the Chaldean Gabareh (Ozymandias Press 2018), chapter 1, section 3: "Aturia or Assyria proper" was a "small district of a few square miles". "At the period of its greatest expansion, however, the name of 'Assyria' — 'land of the chaldeans' — covered a far greater territory, more than filling the space between the two rivers, from the mountains of Armenia to the alluvial line. This gives a length of 350 miles by a breadth, between the Euphrates and the Zagros, varying from above 300 to 170 miles. 'The area was probably not less than 75,000 square miles'."
britannica.com
Encyclopaedia Britannica "The state was finally destroyed by a Babylonian-Median led coalition in 612–609 BC."
