Eze 38:17
This is what the Sovereign LORD says: Are you not the one I spoke of in former days by my servants the prophets of Israel? At that time they prophesied for years that I would bring you against them.
OT prophets spoke of Gog by another name that would come against Israel. Word search biblegateway.com for “the Assyrian;” (the NIV) he is Gog.
According to Nahum 1:11 (compared with Nahum 1:1) the Assyrian comes out of Nineveh. Today, a thriving metropolis exists at the ruins of ancient Nineveh. That Metropolis is called Mosul, and is the center of the insurgency in Iraq.
According to Ezekiel 38:2, Gog is "of the land of Magog." Josephus said that Magog founded the Magogites, but that the Greeks called them Scythians. (“Jewish Antiquities,” by Flavius Josephus, Book 1, chapter 6, sec. 123) The Scythians were an ethnic group well known to modern historians. They inhabited the steppe lands of what is now known as the Ukraine, that is, in Russia.
So Gog and "the Assyrian come from entirely different places." They also attack at different times, and direct their artacks toward different locations in Israel. But the scriptural details that prove these things would take too much space for this post.
Your summation after extensive research on the identity of Gog:
From a map in The Bible Knowledge Commentary by Walvoord and Zuck; Gomer is northern Turkey, Meshech western Turkey, Tubal and Beth Togarmah eastern Turkey. The land of Magog encompasses all these lands including the northwestern corner of Syria. The invading force may include Azerbaijan which is Muslim but not Georgia which is Orthodox or Armenia which is Apostolic. The Assyrian, as Gog, will join forces from the descendents of Japhet who dwelled in most of Turkey after the flood (Gen 10:1-3).
Turkey has 500,000 armed soldiers and is adding another 500,000 men to their ranks. They will be the “great company” from the north invading Israel mid way into the 7 year covenant (38:4).
I have no idea where Walvord and Zurk got the idea that Gomer was ever located in modern day Turkey. The ancient documents locate them in an entirely different region. Biblical Gomer was called Gamer in the Armenian literature, Gammer in the Assyrian literature, and Cimmer in the Greek literature.
The Cimmerians were also an ethnic group well known to modern historians. They were the ancestors of the ethnic group that the Romans called the Gauls, and these were the ancestors of the modern day Celts, who are also called Kelts. This race is the root stock of most of western Europe (except Germany, Italy, and Spain). This also makes them the root stock of most of North America and Australia. So "all the lands of Gomer" includes the heart of western Europe, North America, and Australia.
If you skip the commentaries on prophecy, which all have an agenda to prove, and just study what the historians, who (in such cases as this) have no agenda to prove, you will see that they have concluded exactly what I found in my own personal research.
But Walvord and Zurk were correct in locating ancient Meshech and Tubal in modern day Turkey. But this only applies to their ancient locations. The Turks took over this area in the mid to late eleventh century. As they invaded, they became so famous for their ruthless cruelty that the populationa of these ares fled en masse. Since they were invading from the south, the only direction to go was north, into what is now Russia. This is documented at length in the book “Colophons of Armenian Manuscripts, 1301-1480,” by Avedias K. Sanjian, Cambridge: Harvard University Press, 1969. (A colophon is a note added at the beginning or end of a manuscript, telling who copied it. These are of historical interest because they often included comments about the conditions under which the manuscript was copied.)
It is interesting to note that The name Moscow first appears in Russian history about a hundred years later, as an entry for the year 1147 in “The Nikonian Chronicle.”(Nikonian Chronicle,” trans. by Serg A. and Betty Jean Zenkovsky, vol. 2, pg. 27. Princeton: The Kingston Press, 1982.) This chronicle was written in the years 1520-1550. It lists the Meschera as a tribe living along the Oka River, which passes about 60 miles south of Moscow. (Nikonian Chronicle,” trans. by Serg A. and Betty Jean Zenkovsky, vol. 1, pg. 7. Princeton: The Kingston Press, 1982.) “The Russian Primary Chronicle,” written in 1116, lists the tribes in this area, but this name is not included. (“The Russian Primary Chronicle, Laurentian Text,” copied in 1377 from the 1116 text. trans. and edited by Samuel Hazzard Cross and Olgerd P. Sherbowitz-Wetzor, pg. 55. Cambridge,: The Mediaeval Academy of America, 1953.) The absence of any form of the name Meshech from a description of this area made at approximately the time of the Moslem invasion, coupled with its appearance soon after, strongly suggests that Moschi refugees from Cappadocia and Pontus settled there.
Likewise, the name Tubal seems to be the source of the name of the river Tobol, and of Tobolsk, which was founded about the middle of the sixteenth century, about five hundred years after Tubal fled north from Asia Minor.