What is then taking place on the Earth while the Saints are reigning in Heaven for 1000 years?
During the 1000 years all of the wicked, who were a that time alive, are slain, left dead as refuse "upon the ground" [Jer 25:33], a "great supper" for "all the fowls" [Matt 24:28; Luke 17:37; Rev 19:17], destroyed by the 7 last plagues [Rev 16:1-21], great hail, earthquake [Rev 16:18] and JESUS' Glory and Brightness of HIS 2nd Advent [2 Thess 2:8]...this is why scripture can say, "that the rest of the dead [being all of the wicked], lived not again until the thousand years are finished".
Destruction and judgment are laid heavy upon the earth, in its sin filled and polluted condition, who will be able to live there, "reign" there or want to?
All of the "rest of the dead" [all of the wicked who have ever been] are not alive during the 1000 years. Earth is left desolate, broken down, left in darkness, and only Satan and his angels remain there, "bound" in the barren "wilderness", unable to tempt anyone:
And they shall be gathered together, [as] prisoners are gathered in the pit, and shall be shut up in the prison, and after many days shall they be visited. (Isa 24:22) [All wicked are gathered into bundles, in death, and are "shut up" in graves until 1000 years is over [the "after many days"], then they shall be resurrected]
As therefore the tares are gathered and burned in the fire; so shall it be in the end of this world. (Matt 13:40)
For wheresoever the carcase is, there will the eagles be gathered together. (Matt 24:28)
...Where, Lord? And he said unto them, Wheresoever the body [is], thither will the eagles be gathered together. (Luke 17:37;p)
In flaming fire taking vengeance on them that know not God, and that obey not the gospel of our Lord Jesus Christ: (2 Thess 1:8)
And then shall that Wicked be revealed, whom the Lord shall consume with the spirit of his mouth, and shall destroy with the brightness of his coming: (2 Thess 2:8)
I will utterly consume all [things] from off the land, saith the LORD. (Zep 1:2)
I will consume man and beast; I will consume the fowls of the heaven, and the fishes of the sea, and the stumblingblocks with the wicked; and I will cut off man from off the land, saith the LORD. (Zeph 1:3)
And the idols he shall utterly abolish. (Isa 2:18) [See also Dan 2:34,45]
And they shall go into the holes of the rocks, and into the caves of the earth, for fear of the LORD, and for the glory of his majesty, when he ariseth to shake terribly the earth. (Isa 2:19)
To go into the clefts of the rocks, and into the tops of the ragged rocks, for fear of the LORD, and for the glory of his majesty, when he ariseth to shake terribly the earth. (Isa 2:21)
...he shall smite the earth with the rod of his mouth, and with the breath of his lips shall he slay the wicked. (Isa 11:4;p)
Behold, the LORD maketh the earth empty, and maketh it waste, and turneth it upside down, and scattereth abroad the inhabitants thereof. (Isa 24:1)
The land shall be utterly emptied, and utterly spoiled: for the LORD hath spoken this word. (Isa 24:3)
The earth is utterly broken down, the earth is clean dissolved, the earth is moved exceedingly. (Isa 24:19)
The earth shall reel to and fro like a drunkard, and shall be removed like a cottage; and the transgression thereof shall be heavy upon it; and it shall fall, and not rise again. (Isa 24:20)
Come near, ye nations, to hear; and hearken, ye people: let the earth hear, and all that is therein; the world, and all things that come forth of it. (Isa 34:1)
For the indignation of the LORD [is] upon all nations, and [his] fury upon all their armies: he hath utterly destroyed them, he hath delivered them to the slaughter. (Isa 34:2)
Their slain also shall be cast out, and their stink shall come up out of their carcases, and the mountains shall be melted with their blood. (Isa 34:3)
And all the host of heaven shall be dissolved, and the heavens shall be rolled together as a scroll: and all their host shall fall down, as the leaf falleth off from the vine, and as a falling [fig] from the fig tree. (Isa 34:4)
And the streams thereof shall be turned into pitch, and the dust thereof into brimstone, and the land thereof shall become burning pitch. (Isa 34:9)
I beheld the earth, and, lo, [it was] without form, and void; and the heavens, and they [had] no light. (Jer 4:23)
I beheld, and, lo, [there was] no man, and all the birds of the heavens were fled. (Jer 4:25)
I beheld, and, lo, the fruitful place [was] a wilderness, and all the cities thereof were broken down at the presence of the LORD, [and] by his fierce anger. (Jer 4:26)
For thus hath the LORD said, The whole land shall be desolate; yet will I not make a full end. (Jer 4:27) [The full end comes after the 1,000 years]
For this shall the earth mourn, and the heavens above be black: because I have spoken [it], I have purposed [it], and will not repent, neither will I turn back from it. (Jer 4:28)
The whole city shall flee for the noise of the horsemen and bowmen; they shall go into thickets, and climb up upon the rocks: every city [shall be] forsaken, and not a man dwell therein. (Jer 4:29)
And the slain of the LORD shall be at that day from [one] end of the earth even unto the [other] end of the earth: they shall not be lamented, neither gathered, nor buried; they shall be dung upon the ground. (Jer 25:33)
In the 2nd Advent of JESUS [which begins the 1,000 years], a great and mighty earthquake rocks the world and the 1st Great Resurrection happens [Rev 20:4-6]:
And there were voices, and thunders, and lightnings; and there was a great earthquake, such as was not since men were upon the earth, so mighty an earthquake, [and] so great. (Rev 16:8)
And the great city was divided into three parts, and the cities of the nations fell:... (Rev 16:9;p)
And every island fled away, and the mountains were not found. (Rev 16:20)
And there fell upon men a great hail out of heaven, [every stone] about the weight of a talent: and men blasphemed God because of the plague of the hail; for the plague thereof was exceeding great. (Rev 16:21)
With these passages how can there be a "1000 years" "reign" of peace on the Earth by anyone? For scripture continues by clearly saying:
But as the days of Noe [were], so shall also the coming of the Son of man be. (Matt 24:37)
For as in the days that were before the flood they were eating and drinking, marrying and giving in marriage, until the day that Noe entered into the ark, (Matt 24:38)
And knew not until the flood came, and took them all away; so shall also the coming of the Son of man be. (Matt 24:39)
They did eat, they drank, they married wives, they were given in marriage, until the day that Noe entered into the ark, and the flood came, and destroyed them all. (Luke 17:27)
Likewise also as it was in the days of Lot; they did eat, they drank, they bought, they sold, they planted, they builded; (Luke 17:28)
But the same day that Lot went out of Sodom it rained fire and brimstone from heaven, and destroyed [them] all. (Luke 17:29)
Even thus shall it be in the day when the Son of man is revealed. (Luke 17:30)
For when they shall say, Peace and safety; then sudden destruction cometh upon them, as travail upon a woman with child; and they shall not escape. (1 Thess 5:3)
Satan [typological scapegoat, `aza'zel, not a sacrifice for sin, but ultimately responsible for all sin] then, after the Saints are "caught up" "into the air" and the wicked are "brought low" and "slain" [to await their final sentencing in the Second resurrection after the 1000 years], is bound by his surrounding circumstance in the "1000 years" on the desolate Earth, the "wilderness" a "land not inhabited" [see Jer 4:23-29, 25:33], where was once the "fruitful place", and he is bound and led away, just as Lev 16 and Rev 20:1-3 reveal [for events beforehand compare also Lev 16:17 to Rev 15:8, and also Lev 16:20 with JESUS coming out of Heaven to Heb 9:28]:
And Aaron shall cast lots upon the two goats; one lot for the LORD, and the other lot for the scapegoat. (Lev 16:8)
But the goat, on which the lot fell to be the scapegoat, shall be presented alive before the LORD, to make an atonement with him, [and] to let him go for a scapegoat into the wilderness. (Lev 16:10)
And when he hath made an end of reconciling the holy [place], and the tabernacle of the congregation, and the altar, he shall bring the live goat: (Lev 16:20) [compare]
Then I saw an angel coming down from heaven, having the key to the bottomless pit and a great chain in his hand. (Rev 20:1)
And Aaron shall lay both his hands upon the head of the live goat, and confess over him all the iniquities of the children of Israel, and all their transgressions in all their sins, putting them upon the head of the goat, and shall send [him] away by the hand of a fit man into the wilderness: (Lev 16:21)
And the goat shall bear upon him all their iniquities unto a land not inhabited: and he shall let go the goat in the wilderness. (Lev 16:22) [compare]
And he laid hold on the dragon, that old serpent, which is the Devil, and Satan, and bound him a thousand years, (Rev 20:2)
And cast him into the bottomless pit, and shut him up, and set a seal upon him, that he should deceive the nations no more, till the thousand years should be fulfilled: and after that he must be loosed a little season. (Rev 20:3)