We believe that the thousand years span the time between the first and second resurrections.

“At the coming of Christ the wicked are blotted from the face of the whole earth-consumed with the spirit of His mouth and destroyed by the brightness of His glory.” – The Great Controversy, p. 657. 
2 Thessalonians 1:6-8 – 
Seeing it is a righteous thing with God to recompense tribulation to them that trouble you; And to you who are troubled rest with us, when the Lord Jesus shall be revealed from heaven with his mighty angels, In flaming fire taking vengeance on them that know not God, and that obey not the gospel of our Lord Jesus Christ.
2 Thessalonians 2:8 – 
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: 
Isaiah 24:12, 22 – 
In the city is left desolation, and the gate is smitten with destruction… 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. 

During this time no more human life will exist on this earth. As a result of mighty natural catastrophes, the earth will be in a condition of complete desolation. Jeremiah 4:23, 24; 25:32, 33.

During the thousand years, the saints live and reign with Christ in heaven and judge the fallen angels and the wicked. The earth will be desolate. Only Satan and his angels will live here. – The Great Controversy, p. 659
Revelation 20:1-3 – 
And I saw an angel come down from heaven, having the key of the bottomless pit and a great chain in his hand. And he laid hold on the dragon, that old serpent, which is the Devil, and Satan, and bound him a thousand years, 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.

At the end of the thousand years, Christ will descend to our earth with all the saints. Then the wicked will be resurrected from the dead. After that, the Holy City will come down; and Satan and his angels, with the resurrected wicked, will encircle the Holy City. God will send fire from heaven, and sin and sinners will be forever destroyed, through which the earth will be cleansed. 
Revelation 20:4, 5, first part – 
And I saw thrones, and they sat upon them, and judgment was given unto them: and I saw the souls of them that were beheaded for the witness of Jesus, and for the word of God, and which had not worshipped the beast, neither his image, neither had received his mark upon their foreheads, or in their hands; and they lived and reigned with Christ a thousand years. But the rest of the dead lived not again until the thousand years were finished…
Revelation 20: 7-10 – 
And when the thousand years are expired, Satan shall be loosed out of his prison, And shall go out to deceive the nations which are in the four quarters of the earth, Gog, and Magog, to gather them together to battle: the number of whom is as the sand of the sea. And they went up on the breadth of the earth, and compassed the camp of the saints about, and the beloved city: and fire came down from God out of heaven, and devoured them. And the devil that deceived them was cast into the lake of fire and brimstone, where the beast and the false prophet are, and shall be tormented day and night for ever and ever. 
Malachi 4:1, 3 – 
For, behold, the day cometh, that shall burn as an oven; and all the proud, yea, and all that do wickedly, shall be stubble: and the day that cometh shall burn them up, saith the LORD of hosts, that it shall leave them neither root nor branch. But unto you that fear my name shall the Sun of righteousness arise with healing in his wings; and ye shall go forth, and grow up as calves of the stall. And ye shall tread down the wicked; for they shall be ashes under the soles of your feet in the day that I shall do this, saith the LORD of hosts.